diff --git a/program/lib/Roundcube/rcube_imap_generic.php b/program/lib/Roundcube/rcube_imap_generic.php
index ab0603fdd..84d094460 100644
--- a/program/lib/Roundcube/rcube_imap_generic.php
+++ b/program/lib/Roundcube/rcube_imap_generic.php
@@ -1,4189 +1,4190 @@
 <?php
 
 /**
  +-----------------------------------------------------------------------+
  | This file is part of the Roundcube Webmail client                     |
  |                                                                       |
  | Copyright (C) The Roundcube Dev Team                                  |
  | Copyright (C) Kolab Systems AG                                        |
  |                                                                       |
  | Licensed under the GNU General Public License version 3 or            |
  | any later version with exceptions for skins & plugins.                |
  | See the README file for a full license statement.                     |
  |                                                                       |
  | PURPOSE:                                                              |
  |   Provide alternative IMAP library that doesn't rely on the standard  |
  |   C-Client based version. This allows to function regardless          |
  |   of whether or not the PHP build it's running on has IMAP            |
  |   functionality built-in.                                             |
  |                                                                       |
  |   Based on Iloha IMAP Library. See http://ilohamail.org/ for details  |
  +-----------------------------------------------------------------------+
  | Author: Aleksander Machniak <alec@alec.pl>                            |
  | Author: Ryo Chijiiwa <Ryo@IlohaMail.org>                              |
  +-----------------------------------------------------------------------+
 */
 
 /**
  * PHP based wrapper class to connect to an IMAP server
  *
  * @package    Framework
  * @subpackage Storage
  */
 class rcube_imap_generic
 {
     public $error;
     public $errornum;
     public $result;
     public $resultcode;
     public $selected;
     public $data  = [];
     public $flags = [
         'SEEN'      => '\\Seen',
         'DELETED'   => '\\Deleted',
         'ANSWERED'  => '\\Answered',
         'DRAFT'     => '\\Draft',
         'FLAGGED'   => '\\Flagged',
         'FORWARDED' => '$Forwarded',
         'MDNSENT'   => '$MDNSent',
         '*'         => '\\*',
     ];
 
     protected $fp;
     protected $host;
     protected $user;
     protected $cmd_tag;
     protected $cmd_num = 0;
     protected $resourceid;
     protected $extensions_enabled;
     protected $prefs             = [];
     protected $logged            = false;
     protected $capability        = [];
     protected $capability_read   = false;
     protected $debug             = false;
     protected $debug_handler     = false;
 
     const ERROR_OK       = 0;
     const ERROR_NO       = -1;
     const ERROR_BAD      = -2;
     const ERROR_BYE      = -3;
     const ERROR_UNKNOWN  = -4;
     const ERROR_COMMAND  = -5;
     const ERROR_READONLY = -6;
 
     const COMMAND_NORESPONSE = 1;
     const COMMAND_CAPABILITY = 2;
     const COMMAND_LASTLINE   = 4;
     const COMMAND_ANONYMIZED = 8;
 
     const DEBUG_LINE_LENGTH = 4098; // 4KB + 2B for \r\n
 
 
     /**
      * Send simple (one line) command to the connection stream
      *
      * @param string $string     Command string
      * @param bool   $endln      True if CRLF need to be added at the end of command
      * @param bool   $anonymized Don't write the given data to log but a placeholder
      *
      * @param int Number of bytes sent, False on error
      */
     protected function putLine($string, $endln = true, $anonymized = false)
     {
         if (!$this->fp) {
             return false;
         }
 
         if ($this->debug) {
             // anonymize the sent command for logging
             $cut = $endln ? 2 : 0;
             if ($anonymized && preg_match('/^(A\d+ (?:[A-Z]+ )+)(.+)/', $string, $m)) {
                 $log = $m[1] . sprintf('****** [%d]', strlen($m[2]) - $cut);
             }
             else if ($anonymized) {
                 $log = sprintf('****** [%d]', strlen($string) - $cut);
             }
             else {
                 $log = rtrim($string);
             }
 
             $this->debug('C: ' . $log);
         }
 
         if ($endln) {
             $string .= "\r\n";
         }
 
         $res = fwrite($this->fp, $string);
 
         if ($res === false) {
             $this->closeSocket();
         }
 
         return $res;
     }
 
     /**
      * Send command to the connection stream with Command Continuation
      * Requests (RFC3501 7.5) and LITERAL+ (RFC2088) and LITERAL- (RFC7888) support.
      *
      * @param string $string     Command string
      * @param bool   $endln      True if CRLF need to be added at the end of command
      * @param bool   $anonymized Don't write the given data to log but a placeholder
      *
      * @return int|bool Number of bytes sent, False on error
      */
     protected function putLineC($string, $endln = true, $anonymized = false)
     {
         if (!$this->fp) {
             return false;
         }
 
         if ($endln) {
             $string .= "\r\n";
         }
 
         $res = 0;
         if ($parts = preg_split('/(\{[0-9]+\}\r\n)/m', $string, -1, PREG_SPLIT_DELIM_CAPTURE)) {
             for ($i = 0, $cnt = count($parts); $i < $cnt; $i++) {
                 if ($i + 1 < $cnt && preg_match('/^\{([0-9]+)\}\r\n$/', $parts[$i+1], $matches)) {
                     // LITERAL+/LITERAL- support
                     $literal_plus = false;
                     if (
                         !empty($this->prefs['literal+'])
                         || (!empty($this->prefs['literal-']) && $matches[1] <= 4096)
                     ) {
                         $parts[$i+1] = sprintf("{%d+}\r\n", $matches[1]);
                         $literal_plus = true;
                     }
 
                     $bytes = $this->putLine($parts[$i].$parts[$i+1], false, $anonymized);
                     if ($bytes === false) {
                         return false;
                     }
 
                     $res += $bytes;
 
                     // don't wait if server supports LITERAL+ capability
                     if (!$literal_plus) {
                         $line = $this->readLine(1000);
                         // handle error in command
                         if (!isset($line[0]) || $line[0] != '+') {
                             return false;
                         }
                     }
 
                     $i++;
                 }
                 else {
                     $bytes = $this->putLine($parts[$i], false, $anonymized);
                     if ($bytes === false) {
                         return false;
                     }
 
                     $res += $bytes;
                 }
             }
         }
 
         return $res;
     }
 
     /**
      * Reads line from the connection stream
      *
      * @param int $size Buffer size
      *
      * @return string Line of text response
      */
     protected function readLine($size = 1024)
     {
         $line = '';
 
         if (!$size) {
             $size = 1024;
         }
 
         do {
             if ($this->eof()) {
                 return $line ?: null;
             }
 
             $buffer = fgets($this->fp, $size);
 
             if ($buffer === false) {
                 $this->closeSocket();
                 break;
             }
 
             if ($this->debug) {
                 $this->debug('S: '. rtrim($buffer));
             }
 
             $line .= $buffer;
         }
         while (substr($buffer, -1) != "\n");
 
         return $line;
     }
 
     /**
      * Reads a line of data from the connection stream including all
      * string continuation literals.
      *
      * @param int $size Buffer size
      *
      * @return string Line of text response
      */
     protected function readFullLine($size = 1024)
     {
         $line = $this->readLine($size);
 
         // include all string literals untile the real end of "line"
         while (preg_match('/\{([0-9]+)\}\r\n$/', $line, $m)) {
             $bytes = $m[1];
             $out   = '';
 
             while (strlen($out) < $bytes) {
                 $out = $this->readBytes($bytes);
                 if ($out === null) {
                     break;
                 }
 
                 $line .= $out;
             }
 
             $line .= $this->readLine($size);
         }
 
         return $line;
     }
 
     /**
      * Reads more data from the connection stream when provided
      * data contain string literal
      *
      * @param string  $line    Response text
      * @param bool    $escape  Enables escaping
      *
      * @return string Line of text response
      */
     protected function multLine($line, $escape = false)
     {
         $line = rtrim($line);
         if (preg_match('/\{([0-9]+)\}$/', $line, $m)) {
             $out   = '';
             $str   = substr($line, 0, -strlen($m[0]));
             $bytes = $m[1];
 
             while (strlen($out) < $bytes) {
                 $line = $this->readBytes($bytes);
                 if ($line === null) {
                     break;
                 }
 
                 $out .= $line;
             }
 
             $line = $str . ($escape ? $this->escape($out) : $out);
         }
 
         return $line;
     }
 
     /**
      * Reads specified number of bytes from the connection stream
      *
      * @param int $bytes Number of bytes to get
      *
      * @return string Response text
      */
     protected function readBytes($bytes)
     {
         $data = '';
         $len  = 0;
 
         while ($len < $bytes && !$this->eof()) {
             $d = fread($this->fp, $bytes-$len);
             if ($this->debug) {
                 $this->debug('S: '. $d);
             }
             $data .= $d;
             $data_len = strlen($data);
             if ($len == $data_len) {
                 break; // nothing was read -> exit to avoid apache lockups
             }
             $len = $data_len;
         }
 
         return $data;
     }
 
     /**
      * Reads complete response to the IMAP command
      *
      * @param array $untagged Will be filled with untagged response lines
      *
      * @return string Response text
      */
     protected function readReply(&$untagged = null)
     {
         while (true) {
             $line = trim($this->readLine(1024));
             // store untagged response lines
             if (isset($line[0]) && $line[0] == '*') {
                 $untagged[] = $line;
             }
             else {
                 break;
             }
         }
 
         if ($untagged) {
             $untagged = implode("\n", $untagged);
         }
 
         return $line;
     }
 
     /**
      * Response parser.
      *
      * @param string $string     Response text
      * @param string $err_prefix Error message prefix
      *
      * @return int Response status
      */
     protected function parseResult($string, $err_prefix = '')
     {
         if (preg_match('/^[a-z0-9*]+ (OK|NO|BAD|BYE)(.*)$/i', trim($string), $matches)) {
             $res = strtoupper($matches[1]);
             $str = trim($matches[2]);
 
             if ($res == 'OK') {
                 $this->errornum = self::ERROR_OK;
             }
             else if ($res == 'NO') {
                 $this->errornum = self::ERROR_NO;
             }
             else if ($res == 'BAD') {
                 $this->errornum = self::ERROR_BAD;
             }
             else if ($res == 'BYE') {
                 $this->closeSocket();
                 $this->errornum = self::ERROR_BYE;
             }
 
             if ($str) {
                 $str = trim($str);
                 // get response string and code (RFC5530)
                 if (preg_match("/^\[([a-z-]+)\]/i", $str, $m)) {
                     $this->resultcode = strtoupper($m[1]);
                     $str = trim(substr($str, strlen($m[1]) + 2));
                 }
                 else {
                     $this->resultcode = null;
                     // parse response for [APPENDUID 1204196876 3456]
                     if (preg_match("/^\[APPENDUID [0-9]+ ([0-9]+)\]/i", $str, $m)) {
                         $this->data['APPENDUID'] = $m[1];
                     }
                     // parse response for [COPYUID 1204196876 3456:3457 123:124]
                     else if (preg_match("/^\[COPYUID [0-9]+ ([0-9,:]+) ([0-9,:]+)\]/i", $str, $m)) {
                         $this->data['COPYUID'] = [$m[1], $m[2]];
                     }
                 }
 
                 $this->result = $str;
 
                 if ($this->errornum != self::ERROR_OK) {
                     $this->error = $err_prefix ? $err_prefix.$str : $str;
                 }
             }
 
             return $this->errornum;
         }
 
         return self::ERROR_UNKNOWN;
     }
 
     /**
      * Checks connection stream state.
      *
      * @return bool True if connection is closed
      */
     protected function eof()
     {
         if (!is_resource($this->fp)) {
             return true;
         }
 
         // If a connection opened by fsockopen() wasn't closed
         // by the server, feof() will hang.
         $start = microtime(true);
 
         if (feof($this->fp) ||
             ($this->prefs['timeout'] && (microtime(true) - $start > $this->prefs['timeout']))
         ) {
             $this->closeSocket();
             return true;
         }
 
         return false;
     }
 
     /**
      * Closes connection stream.
      */
     protected function closeSocket()
     {
         if ($this->fp) {
             fclose($this->fp);
             $this->fp = null;
         }
     }
 
     /**
      * Error code/message setter.
      */
     protected function setError($code, $msg = '')
     {
         $this->errornum = $code;
         $this->error    = $msg;
 
         return $code;
     }
 
     /**
      * Checks response status.
      * Checks if command response line starts with specified prefix (or * BYE/BAD)
      *
      * @param string $string   Response text
      * @param string $match    Prefix to match with (case-sensitive)
      * @param bool   $error    Enables BYE/BAD checking
      * @param bool   $nonempty Enables empty response checking
      *
      * @return bool True any check is true or connection is closed.
      */
     protected function startsWith($string, $match, $error = false, $nonempty = false)
     {
         if (!$this->fp) {
             return true;
         }
 
         if (strncmp($string, $match, strlen($match)) == 0) {
             return true;
         }
 
         if ($error && preg_match('/^\* (BYE|BAD) /i', $string, $m)) {
             if (strtoupper($m[1]) == 'BYE') {
                 $this->closeSocket();
             }
             return true;
         }
 
         if ($nonempty && !strlen($string)) {
             return true;
         }
 
         return false;
     }
 
     /**
      * Capabilities checker
      */
     protected function hasCapability($name)
     {
         if (empty($this->capability) || empty($name)) {
             return false;
         }
 
         if (in_array($name, $this->capability)) {
             return true;
         }
         else if (strpos($name, '=')) {
             return false;
         }
 
         $result = [];
         foreach ($this->capability as $cap) {
             $entry = explode('=', $cap);
             if ($entry[0] == $name) {
                 $result[] = $entry[1];
             }
         }
 
         return $result ?: false;
     }
 
     /**
      * Capabilities checker
      *
      * @param string $name Capability name
      *
      * @return mixed Capability values array for key=value pairs, true/false for others
      */
     public function getCapability($name)
     {
         $result = $this->hasCapability($name);
 
         if (!empty($result)) {
             return $result;
         }
         else if ($this->capability_read) {
             return false;
         }
 
         // get capabilities (only once) because initial
         // optional CAPABILITY response may differ
         $result = $this->execute('CAPABILITY');
 
         if ($result[0] == self::ERROR_OK) {
             $this->parseCapability($result[1]);
         }
 
         $this->capability_read = true;
 
         return $this->hasCapability($name);
     }
 
     /**
      * Clears detected server capabilities
      */
     public function clearCapability()
     {
         $this->capability        = [];
         $this->capability_read = false;
     }
 
     /**
      * DIGEST-MD5/CRAM-MD5/PLAIN Authentication
      *
      * @param string $user Username
      * @param string $pass Password
      * @param string $type Authentication type (PLAIN/CRAM-MD5/DIGEST-MD5)
      *
      * @return resource Connection resource on success, error code on error
      */
     protected function authenticate($user, $pass, $type = 'PLAIN')
     {
         if ($type == 'CRAM-MD5' || $type == 'DIGEST-MD5') {
             if ($type == 'DIGEST-MD5' && !class_exists('Auth_SASL')) {
                 return $this->setError(self::ERROR_BYE,
                     "The Auth_SASL package is required for DIGEST-MD5 authentication");
             }
 
             $this->putLine($this->nextTag() . " AUTHENTICATE $type");
             $line = trim($this->readReply());
 
             if ($line[0] == '+') {
                 $challenge = substr($line, 2);
             }
             else {
                 return $this->parseResult($line);
             }
 
             if ($type == 'CRAM-MD5') {
                 // RFC2195: CRAM-MD5
                 $ipad = '';
                 $opad = '';
                 $xor  = function($str1, $str2) {
                     $result = '';
                     $size   = strlen($str1);
                     for ($i=0; $i<$size; $i++) {
                         $result .= chr(ord($str1[$i]) ^ ord($str2[$i]));
                     }
                     return $result;
                 };
 
                 // initialize ipad, opad
                 for ($i=0; $i<64; $i++) {
                     $ipad .= chr(0x36);
                     $opad .= chr(0x5C);
                 }
 
                 // pad $pass so it's 64 bytes
                 $pass = str_pad($pass, 64, chr(0));
 
                 // generate hash
                 $hash  = md5($xor($pass, $opad) . pack("H*",
                     md5($xor($pass, $ipad) . base64_decode($challenge))));
                 $reply = base64_encode($user . ' ' . $hash);
 
                 // send result
                 $this->putLine($reply, true, true);
             }
             else {
                 // RFC2831: DIGEST-MD5
                 // proxy authorization
                 if (!empty($this->prefs['auth_cid'])) {
                     $authc = $this->prefs['auth_cid'];
                     $pass  = $this->prefs['auth_pw'];
                 }
                 else {
                     $authc = $user;
                     $user  = '';
                 }
 
                 $auth_sasl = new Auth_SASL;
                 $auth_sasl = $auth_sasl->factory('digestmd5');
                 $reply     = base64_encode($auth_sasl->getResponse($authc, $pass,
                     base64_decode($challenge), $this->host, 'imap', $user));
 
                 // send result
                 $this->putLine($reply, true, true);
                 $line = trim($this->readReply());
 
                 if ($line[0] != '+') {
                     return $this->parseResult($line);
                 }
 
                 // check response
                 $challenge = substr($line, 2);
                 $challenge = base64_decode($challenge);
                 if (strpos($challenge, 'rspauth=') === false) {
                     return $this->setError(self::ERROR_BAD,
                         "Unexpected response from server to DIGEST-MD5 response");
                 }
 
                 $this->putLine('');
             }
 
             $line   = $this->readReply();
             $result = $this->parseResult($line);
         }
         else if ($type == 'GSSAPI') {
             if (!extension_loaded('krb5')) {
                 return $this->setError(self::ERROR_BYE,
                     "The krb5 extension is required for GSSAPI authentication");
             }
 
             if (empty($this->prefs['gssapi_cn'])) {
                 return $this->setError(self::ERROR_BYE,
                     "The gssapi_cn parameter is required for GSSAPI authentication");
             }
 
             if (empty($this->prefs['gssapi_context'])) {
                 return $this->setError(self::ERROR_BYE,
                     "The gssapi_context parameter is required for GSSAPI authentication");
             }
 
             putenv('KRB5CCNAME=' . $this->prefs['gssapi_cn']);
 
             try {
                 $ccache = new KRB5CCache();
                 $ccache->open($this->prefs['gssapi_cn']);
                 $gssapicontext = new GSSAPIContext();
                 $gssapicontext->acquireCredentials($ccache);
 
                 $token   = '';
                 $success = $gssapicontext->initSecContext($this->prefs['gssapi_context'], null, null, null, $token);
                 $token   = base64_encode($token);
             }
             catch (Exception $e) {
                 trigger_error($e->getMessage(), E_USER_WARNING);
                 return $this->setError(self::ERROR_BYE, "GSSAPI authentication failed");
             }
 
             $this->putLine($this->nextTag() . " AUTHENTICATE GSSAPI " . $token);
             $line = trim($this->readReply());
 
             if ($line[0] != '+') {
                 return $this->parseResult($line);
             }
 
             try {
                 $itoken = base64_decode(substr($line, 2));
 
                 if (!$gssapicontext->unwrap($itoken, $itoken)) {
                     throw new Exception("GSSAPI SASL input token unwrap failed");
                 }
 
                 if (strlen($itoken) < 4) {
                     throw new Exception("GSSAPI SASL input token invalid");
                 }
 
                 // Integrity/encryption layers are not supported. The first bit
                 // indicates that the server supports "no security layers".
                 // 0x00 should not occur, but support broken implementations.
                 $server_layers = ord($itoken[0]);
                 if ($server_layers && ($server_layers & 0x1) != 0x1) {
                     throw new Exception("Server requires GSSAPI SASL integrity/encryption");
                 }
 
                 // Construct output token. 0x01 in the first octet = SASL layer "none",
                 // zero in the following three octets = no data follows.
                 // See https://github.com/cyrusimap/cyrus-sasl/blob/e41cfb986c1b1935770de554872247453fdbb079/plugins/gssapi.c#L1284
                 if (!$gssapicontext->wrap(pack("CCCC", 0x1, 0, 0, 0), $otoken, true)) {
                     throw new Exception("GSSAPI SASL output token wrap failed");
                 }
             }
             catch (Exception $e) {
                 trigger_error($e->getMessage(), E_USER_WARNING);
                 return $this->setError(self::ERROR_BYE, "GSSAPI authentication failed");
             }
 
             $this->putLine(base64_encode($otoken));
 
             $line   = $this->readReply();
             $result = $this->parseResult($line);
         }
         else if ($type == 'PLAIN') {
             // proxy authorization
             if (!empty($this->prefs['auth_cid'])) {
                 $authc = $this->prefs['auth_cid'];
                 $pass  = $this->prefs['auth_pw'];
             }
             else {
                 $authc = $user;
                 $user  = '';
             }
 
             $reply = base64_encode($user . chr(0) . $authc . chr(0) . $pass);
 
             // RFC 4959 (SASL-IR): save one round trip
             if ($this->getCapability('SASL-IR')) {
                 list($result, $line) = $this->execute("AUTHENTICATE PLAIN", [$reply],
                     self::COMMAND_LASTLINE | self::COMMAND_CAPABILITY | self::COMMAND_ANONYMIZED);
             }
             else {
                 $this->putLine($this->nextTag() . " AUTHENTICATE PLAIN");
                 $line = trim($this->readReply());
 
                 if ($line[0] != '+') {
                     return $this->parseResult($line);
                 }
 
                 // send result, get reply and process it
                 $this->putLine($reply, true, true);
                 $line   = $this->readReply();
                 $result = $this->parseResult($line);
             }
         }
         else if ($type == 'LOGIN') {
             $this->putLine($this->nextTag() . " AUTHENTICATE LOGIN");
 
             $line = trim($this->readReply());
             if ($line[0] != '+') {
                 return $this->parseResult($line);
             }
 
             $this->putLine(base64_encode($user), true, true);
 
             $line = trim($this->readReply());
             if ($line[0] != '+') {
                 return $this->parseResult($line);
             }
 
             // send result, get reply and process it
             $this->putLine(base64_encode($pass), true, true);
 
             $line   = $this->readReply();
             $result = $this->parseResult($line);
         }
         else if ($type == 'XOAUTH2') {
             $auth = base64_encode("user=$user\1auth=$pass\1\1");
             $this->putLine($this->nextTag() . " AUTHENTICATE XOAUTH2 $auth", true, true);
 
             $line = trim($this->readReply());
 
             if ($line[0] == '+') {
                 // send empty line
                 $this->putLine('', true, true);
                 $line = $this->readReply();
             }
 
             $result = $this->parseResult($line);
         }
         else {
             $line  = 'not supported';
             $result = self::ERROR_UNKNOWN;
         }
 
         if ($result === self::ERROR_OK) {
             // optional CAPABILITY response
             if ($line && preg_match('/\[CAPABILITY ([^]]+)\]/i', $line, $matches)) {
                 $this->parseCapability($matches[1], true);
             }
 
             return $this->fp;
         }
 
         return $this->setError($result, "AUTHENTICATE $type: $line");
     }
 
     /**
      * LOGIN Authentication
      *
      * @param string $user Username
      * @param string $pass Password
      *
      * @return resource Connection resource on success, error code on error
      */
     protected function login($user, $password)
     {
         // Prevent from sending credentials in plain text when connection is not secure
         if ($this->getCapability('LOGINDISABLED')) {
             return $this->setError(self::ERROR_BAD, "Login disabled by IMAP server");
         }
 
         list($code, $response) = $this->execute('LOGIN', [$this->escape($user), $this->escape($password)],
             self::COMMAND_CAPABILITY | self::COMMAND_ANONYMIZED);
 
         // re-set capabilities list if untagged CAPABILITY response provided
         if (preg_match('/\* CAPABILITY (.+)/i', $response, $matches)) {
             $this->parseCapability($matches[1], true);
         }
 
         if ($code == self::ERROR_OK) {
             return $this->fp;
         }
 
         return $code;
     }
 
     /**
      * Detects hierarchy delimiter
      *
      * @return string The delimiter
      */
     public function getHierarchyDelimiter()
     {
         if (!empty($this->prefs['delimiter'])) {
             return $this->prefs['delimiter'];
         }
 
         // try (LIST "" ""), should return delimiter (RFC2060 Sec 6.3.8)
         list($code, $response) = $this->execute('LIST', [$this->escape(''), $this->escape('')]);
 
         if ($code == self::ERROR_OK) {
             $args = $this->tokenizeResponse($response, 4);
             $delimiter = $args[3];
 
             if (strlen($delimiter) > 0) {
                 return ($this->prefs['delimiter'] = $delimiter);
             }
         }
     }
 
     /**
      * NAMESPACE handler (RFC 2342)
      *
      * @return array Namespace data hash (personal, other, shared)
      */
     public function getNamespace()
     {
         if (array_key_exists('namespace', $this->prefs)) {
             return $this->prefs['namespace'];
         }
 
         if (!$this->getCapability('NAMESPACE')) {
             return self::ERROR_BAD;
         }
 
         list($code, $response) = $this->execute('NAMESPACE');
 
         if ($code == self::ERROR_OK && preg_match('/^\* NAMESPACE /', $response)) {
             $response = substr($response, 11);
             $data     = $this->tokenizeResponse($response);
         }
 
         if (!isset($data) || !is_array($data)) {
             return $code;
         }
 
         $this->prefs['namespace'] = [
             'personal' => $data[0],
             'other'    => $data[1],
             'shared'   => $data[2],
         ];
 
         return $this->prefs['namespace'];
     }
 
     /**
      * Connects to IMAP server and authenticates.
      *
      * @param string $host     Server hostname or IP
      * @param string $user     User name
      * @param string $password Password
      * @param array  $options  Connection and class options
      *
      * @return bool True on success, False on failure
      */
     public function connect($host, $user, $password, $options = [])
     {
         // configure
         $this->set_prefs($options);
 
         $this->host     = $host;
         $this->user     = $user;
         $this->logged   = false;
         $this->selected = null;
 
         // check input
         if (empty($host)) {
             $this->setError(self::ERROR_BAD, "Empty host");
             return false;
         }
 
         if (empty($user)) {
             $this->setError(self::ERROR_NO, "Empty user");
             return false;
         }
 
         if (empty($password) && empty($options['gssapi_cn'])) {
             $this->setError(self::ERROR_NO, "Empty password");
             return false;
         }
 
         // Connect
         if (!$this->_connect($host)) {
             return false;
         }
 
         // Send pre authentication ID info (#7860)
         if (!empty($this->prefs['preauth_ident']) && $this->getCapability('ID')) {
             $this->data['ID'] = $this->id($this->prefs['preauth_ident']);
         }
 
         $auth_method  = $this->prefs['auth_type'];
         $auth_methods = [];
         $result       = null;
 
         // check for supported auth methods
         if (!$auth_method || $auth_method == 'CHECK') {
             if ($auth_caps = $this->getCapability('AUTH')) {
                 $auth_methods = $auth_caps;
             }
 
             // Use best (for security) supported authentication method
             $all_methods = ['DIGEST-MD5', 'CRAM-MD5', 'CRAM_MD5', 'PLAIN', 'LOGIN'];
 
             if (!empty($this->prefs['gssapi_cn'])) {
                 array_unshift($all_methods, 'GSSAPI');
             }
 
             foreach ($all_methods as $auth_method) {
                 if (in_array($auth_method, $auth_methods)) {
                     break;
                 }
             }
 
             // Prefer LOGIN over AUTHENTICATE LOGIN for performance reasons
             if ($auth_method == 'LOGIN' && !$this->getCapability('LOGINDISABLED')) {
                 $auth_method = 'IMAP';
             }
         }
 
         // pre-login capabilities can be not complete
         $this->capability_read = false;
 
         // Authenticate
         switch ($auth_method) {
             case 'CRAM_MD5':
                 $auth_method = 'CRAM-MD5';
             case 'CRAM-MD5':
             case 'DIGEST-MD5':
             case 'GSSAPI':
             case 'PLAIN':
             case 'LOGIN':
             case 'XOAUTH2':
                 $result = $this->authenticate($user, $password, $auth_method);
                 break;
 
             case 'IMAP':
                 $result = $this->login($user, $password);
                 break;
 
             default:
                 $this->setError(self::ERROR_BAD, "Configuration error. Unknown auth method: $auth_method");
         }
 
         // Connected and authenticated
         if (is_resource($result)) {
             if (!empty($this->prefs['force_caps'])) {
                 $this->clearCapability();
             }
 
             $this->logged = true;
 
             // Send ID info after authentication to ensure reliable result (#7517)
             if (!empty($this->prefs['ident']) && $this->getCapability('ID')) {
                 $this->data['ID'] = $this->id($this->prefs['ident']);
             }
 
             return true;
         }
 
         $this->closeConnection();
 
         return false;
     }
 
     /**
      * Connects to IMAP server.
      *
      * @param string $host Server hostname or IP
      *
      * @return bool True on success, False on failure
      */
     protected function _connect($host)
     {
         // initialize connection
         $this->error    = '';
         $this->errornum = self::ERROR_OK;
 
         if (empty($this->prefs['port'])) {
             $this->prefs['port'] = 143;
         }
 
         // check for SSL
         if (!empty($this->prefs['ssl_mode']) && $this->prefs['ssl_mode'] != 'tls') {
             $host = $this->prefs['ssl_mode'] . '://' . $host;
         }
 
         if (empty($this->prefs['timeout']) || $this->prefs['timeout'] < 0) {
             $this->prefs['timeout'] = max(0, intval(ini_get('default_socket_timeout')));
         }
 
         if ($this->debug) {
             // set connection identifier for debug output
             $this->resourceid = strtoupper(substr(md5(microtime() . $host . $this->user), 0, 4));
 
             $_host = ($this->prefs['ssl_mode'] == 'tls' ? 'tls://' : '') . $host . ':' . $this->prefs['port'];
             $this->debug("Connecting to $_host...");
         }
 
         if (!empty($this->prefs['socket_options'])) {
             $options  = array_intersect_key($this->prefs['socket_options'], ['ssl' => 1]);
             $context  = stream_context_create($options);
             $this->fp = stream_socket_client($host . ':' . $this->prefs['port'], $errno, $errstr,
                 $this->prefs['timeout'], STREAM_CLIENT_CONNECT, $context);
         }
         else {
             $this->fp = @fsockopen($host, $this->prefs['port'], $errno, $errstr, $this->prefs['timeout']);
         }
 
         if (!$this->fp) {
             $this->setError(self::ERROR_BAD, sprintf("Could not connect to %s:%d: %s",
                 $host, $this->prefs['port'], $errstr ?: "Unknown reason"));
 
             return false;
         }
 
         // insert proxy protocol header, if enabled
         if (!empty($this->prefs['socket_options'])) {
             $proxy_protocol_header = rcube_utils::proxy_protocol_header($this->prefs['socket_options'], $this->fp);
             if (strlen($proxy_protocol_header) > 0) {
                 fwrite($this->fp, $proxy_protocol_header);
             }
         }
         
         if ($this->prefs['timeout'] > 0) {
             stream_set_timeout($this->fp, $this->prefs['timeout']);
         }
 
         $line = trim(fgets($this->fp, 8192));
 
         if ($this->debug && $line) {
             $this->debug('S: '. $line);
         }
 
         // Connected to wrong port or connection error?
         if (!preg_match('/^\* (OK|PREAUTH)/i', $line)) {
             if ($line)
                 $error = sprintf("Wrong startup greeting (%s:%d): %s", $host, $this->prefs['port'], $line);
             else
                 $error = sprintf("Empty startup greeting (%s:%d)", $host, $this->prefs['port']);
 
             $this->setError(self::ERROR_BAD, $error);
             $this->closeConnection();
             return false;
         }
 
         $this->data['GREETING'] = trim(preg_replace('/\[[^\]]+\]\s*/', '', $line));
 
         // RFC3501 [7.1] optional CAPABILITY response
         if (preg_match('/\[CAPABILITY ([^]]+)\]/i', $line, $matches)) {
             $this->parseCapability($matches[1], true);
         }
 
         // TLS connection
         if (isset($this->prefs['ssl_mode']) && $this->prefs['ssl_mode'] == 'tls' && $this->getCapability('STARTTLS')) {
             $res = $this->execute('STARTTLS');
 
             if (empty($res) || $res[0] != self::ERROR_OK) {
                 $this->closeConnection();
                 return false;
             }
 
             if (isset($this->prefs['socket_options']['ssl']['crypto_method'])) {
                 $crypto_method = $this->prefs['socket_options']['ssl']['crypto_method'];
             }
             else {
                 // There is no flag to enable all TLS methods. Net_SMTP
                 // handles enabling TLS similarly.
                 $crypto_method = STREAM_CRYPTO_METHOD_TLS_CLIENT
                     | @STREAM_CRYPTO_METHOD_TLSv1_1_CLIENT
                     | @STREAM_CRYPTO_METHOD_TLSv1_2_CLIENT;
             }
 
             if (!stream_socket_enable_crypto($this->fp, true, $crypto_method)) {
                 $this->setError(self::ERROR_BAD, "Unable to negotiate TLS");
                 $this->closeConnection();
                 return false;
             }
 
             // Now we're secure, capabilities need to be reread
             $this->clearCapability();
         }
 
         return true;
     }
 
     /**
      * Initializes environment
      */
     protected function set_prefs($prefs)
     {
         // set preferences
         if (is_array($prefs)) {
             $this->prefs = $prefs;
         }
 
         // set auth method
         if (!empty($this->prefs['auth_type'])) {
             $this->prefs['auth_type'] = strtoupper($this->prefs['auth_type']);
         }
         else {
             $this->prefs['auth_type'] = 'CHECK';
         }
 
         // disabled capabilities
         if (!empty($this->prefs['disabled_caps'])) {
             $this->prefs['disabled_caps'] = array_map('strtoupper', (array)$this->prefs['disabled_caps']);
         }
 
         // additional message flags
         if (!empty($this->prefs['message_flags'])) {
             $this->flags = array_merge($this->flags, $this->prefs['message_flags']);
             unset($this->prefs['message_flags']);
         }
     }
 
     /**
      * Checks connection status
      *
      * @return bool True if connection is active and user is logged in, False otherwise.
      */
     public function connected()
     {
         return $this->fp && $this->logged;
     }
 
     /**
      * Closes connection with logout.
      */
     public function closeConnection()
     {
         if ($this->logged && $this->putLine($this->nextTag() . ' LOGOUT')) {
             $this->readReply();
         }
 
         $this->closeSocket();
     }
 
     /**
      * Executes SELECT command (if mailbox is already not in selected state)
      *
      * @param string $mailbox      Mailbox name
      * @param array  $qresync_data QRESYNC data (RFC5162)
      *
      * @return bool True on success, false on error
      */
     public function select($mailbox, $qresync_data = null)
     {
         if (!strlen($mailbox)) {
             return false;
         }
 
         if ($this->selected === $mailbox) {
             return true;
         }
 
         $params = [$this->escape($mailbox)];
 
         // QRESYNC data items
         //    0. the last known UIDVALIDITY,
         //    1. the last known modification sequence,
         //    2. the optional set of known UIDs, and
         //    3. an optional parenthesized list of known sequence ranges and their
         //       corresponding UIDs.
         if (!empty($qresync_data)) {
             if (!empty($qresync_data[2])) {
                 $qresync_data[2] = self::compressMessageSet($qresync_data[2]);
             }
 
             $params[] = ['QRESYNC', $qresync_data];
         }
 
         list($code, $response) = $this->execute('SELECT', $params);
 
         if ($code == self::ERROR_OK) {
             $this->clear_mailbox_cache();
 
             $response = explode("\r\n", $response);
             foreach ($response as $line) {
                 if (preg_match('/^\* OK \[/i', $line)) {
                     $pos   = strcspn($line, ' ]', 6);
                     $token = strtoupper(substr($line, 6, $pos));
                     $pos   += 7;
 
                     switch ($token) {
                     case 'UIDNEXT':
                     case 'UIDVALIDITY':
                     case 'UNSEEN':
                         if ($len = strspn($line, '0123456789', $pos)) {
                             $this->data[$token] = (int) substr($line, $pos, $len);
                         }
                         break;
 
                     case 'HIGHESTMODSEQ':
                         if ($len = strspn($line, '0123456789', $pos)) {
                             $this->data[$token] = (string) substr($line, $pos, $len);
                         }
                         break;
 
                     case 'NOMODSEQ':
                         $this->data[$token] = true;
                         break;
 
                     case 'PERMANENTFLAGS':
                         $start = strpos($line, '(', $pos);
                         $end   = strrpos($line, ')');
                         if ($start && $end) {
                             $flags = substr($line, $start + 1, $end - $start - 1);
                             $this->data[$token] = explode(' ', $flags);
                         }
                         break;
                     }
                 }
                 else if (preg_match('/^\* ([0-9]+) (EXISTS|RECENT|FETCH)/i', $line, $match)) {
                     $token = strtoupper($match[2]);
                     switch ($token) {
                     case 'EXISTS':
                     case 'RECENT':
                         $this->data[$token] = (int) $match[1];
                         break;
 
                     case 'FETCH':
                         // QRESYNC FETCH response (RFC5162)
                         $line       = substr($line, strlen($match[0]));
                         $fetch_data = $this->tokenizeResponse($line, 1);
                         $data       = ['id' => $match[1]];
 
                         for ($i=0, $size=count($fetch_data); $i<$size; $i+=2) {
                             $data[strtolower($fetch_data[$i])] = $fetch_data[$i+1];
                         }
 
                         $this->data['QRESYNC'][$data['uid']] = $data;
                         break;
                     }
                 }
                 // QRESYNC VANISHED response (RFC5162)
                 else if (preg_match('/^\* VANISHED [()EARLIER]*/i', $line, $match)) {
                     $line   = substr($line, strlen($match[0]));
                     $v_data = $this->tokenizeResponse($line, 1);
 
                     $this->data['VANISHED'] = $v_data;
                 }
             }
 
             $this->data['READ-WRITE'] = $this->resultcode != 'READ-ONLY';
             $this->selected = $mailbox;
 
             return true;
         }
 
         return false;
     }
 
     /**
      * Executes STATUS command
      *
      * @param string $mailbox Mailbox name
      * @param array  $items   Additional requested item names. By default
      *                        MESSAGES and UNSEEN are requested. Other defined
      *                        in RFC3501: UIDNEXT, UIDVALIDITY, RECENT
      *
      * @return array Status item-value hash
      * @since 0.5-beta
      */
     public function status($mailbox, $items = [])
     {
         if (!strlen($mailbox)) {
             return false;
         }
 
         if (!in_array('MESSAGES', $items)) {
             $items[] = 'MESSAGES';
         }
         if (!in_array('UNSEEN', $items)) {
             $items[] = 'UNSEEN';
         }
 
         list($code, $response) = $this->execute('STATUS',
             [$this->escape($mailbox), '(' . implode(' ', $items) . ')'], 0, '/^\* STATUS /i');
 
         if ($code == self::ERROR_OK && $response) {
             $result   = [];
             $response = substr($response, 9); // remove prefix "* STATUS "
 
             list($mbox, $items) = $this->tokenizeResponse($response, 2);
 
             // Fix for #1487859. Some buggy server returns not quoted
             // folder name with spaces. Let's try to handle this situation
             if (!is_array($items) && ($pos = strpos($response, '(')) !== false) {
                 $response = substr($response, $pos);
                 $items    = $this->tokenizeResponse($response, 1);
             }
 
             if (!is_array($items)) {
                 return $result;
             }
 
             for ($i=0, $len=count($items); $i<$len; $i += 2) {
                 $result[$items[$i]] = $items[$i+1];
             }
 
             $this->data['STATUS:'.$mailbox] = $result;
 
             return $result;
         }
 
         return false;
     }
 
     /**
      * Executes EXPUNGE command
      *
      * @param string       $mailbox  Mailbox name
      * @param string|array $messages Message UIDs to expunge
      *
      * @return bool True on success, False on error
      */
     public function expunge($mailbox, $messages = null)
     {
         if (!$this->select($mailbox)) {
             return false;
         }
 
         if (empty($this->data['READ-WRITE'])) {
             $this->setError(self::ERROR_READONLY, "Mailbox is read-only");
             return false;
         }
 
         // Clear internal status cache
         $this->clear_status_cache($mailbox);
 
         if (!empty($messages) && $messages != '*' && $this->hasCapability('UIDPLUS')) {
             $messages = self::compressMessageSet($messages);
             $result   = $this->execute('UID EXPUNGE', [$messages], self::COMMAND_NORESPONSE);
         }
         else {
             $result = $this->execute('EXPUNGE', null, self::COMMAND_NORESPONSE);
         }
 
         if ($result == self::ERROR_OK) {
             $this->selected = null; // state has changed, need to reselect
             return true;
         }
 
         return false;
     }
 
     /**
      * Executes CLOSE command
      *
      * @return bool True on success, False on error
      * @since 0.5
      */
     public function close()
     {
         $result = $this->execute('CLOSE', null, self::COMMAND_NORESPONSE);
 
         if ($result == self::ERROR_OK) {
             $this->selected = null;
             return true;
         }
 
         return false;
     }
 
     /**
      * Folder subscription (SUBSCRIBE)
      *
      * @param string $mailbox Mailbox name
      *
      * @return bool True on success, False on error
      */
     public function subscribe($mailbox)
     {
         $result = $this->execute('SUBSCRIBE', [$this->escape($mailbox)], self::COMMAND_NORESPONSE);
 
         return $result == self::ERROR_OK;
     }
 
     /**
      * Folder unsubscription (UNSUBSCRIBE)
      *
      * @param string $mailbox Mailbox name
      *
      * @return bool True on success, False on error
      */
     public function unsubscribe($mailbox)
     {
         $result = $this->execute('UNSUBSCRIBE', [$this->escape($mailbox)], self::COMMAND_NORESPONSE);
 
         return $result == self::ERROR_OK;
     }
 
     /**
      * Folder creation (CREATE)
      *
      * @param string $mailbox Mailbox name
      * @param array  $types   Optional folder types (RFC 6154)
      *
      * @return bool True on success, False on error
      */
     public function createFolder($mailbox, $types = null)
     {
         $args = [$this->escape($mailbox)];
 
         // RFC 6154: CREATE-SPECIAL-USE
         if (!empty($types) && $this->getCapability('CREATE-SPECIAL-USE')) {
             $args[] = '(USE (' . implode(' ', $types) . '))';
         }
 
         $result = $this->execute('CREATE', $args, self::COMMAND_NORESPONSE);
 
         return $result == self::ERROR_OK;
     }
 
     /**
      * Folder renaming (RENAME)
      *
      * @param string $mailbox Mailbox name
      *
      * @return bool True on success, False on error
      */
     public function renameFolder($from, $to)
     {
         $result = $this->execute('RENAME', [$this->escape($from), $this->escape($to)], self::COMMAND_NORESPONSE);
 
         return $result == self::ERROR_OK;
     }
 
     /**
      * Executes DELETE command
      *
      * @param string $mailbox Mailbox name
      *
      * @return bool True on success, False on error
      */
     public function deleteFolder($mailbox)
     {
         $result = $this->execute('DELETE', [$this->escape($mailbox)], self::COMMAND_NORESPONSE);
 
         return $result == self::ERROR_OK;
     }
 
     /**
      * Removes all messages in a folder
      *
      * @param string $mailbox Mailbox name
      *
      * @return bool True on success, False on error
      */
     public function clearFolder($mailbox)
     {
         if ($this->countMessages($mailbox) > 0) {
             $res = $this->flag($mailbox, '1:*', 'DELETED');
         }
         else {
             return true;
         }
 
         if (!empty($res)) {
             if ($this->selected === $mailbox) {
                 $res = $this->close();
             }
             else {
                 $res = $this->expunge($mailbox);
             }
 
             return $res;
         }
 
         return false;
     }
 
     /**
      * Returns list of mailboxes
      *
      * @param string $ref         Reference name
      * @param string $mailbox     Mailbox name
      * @param array  $return_opts (see self::_listMailboxes)
      * @param array  $select_opts (see self::_listMailboxes)
      *
      * @return array|bool List of mailboxes or hash of options if STATUS/MYRIGHTS response
      *                    is requested, False on error.
      */
     public function listMailboxes($ref, $mailbox, $return_opts = [], $select_opts = [])
     {
         return $this->_listMailboxes($ref, $mailbox, false, $return_opts, $select_opts);
     }
 
     /**
      * Returns list of subscribed mailboxes
      *
      * @param string $ref         Reference name
      * @param string $mailbox     Mailbox name
      * @param array  $return_opts (see self::_listMailboxes)
      *
      * @return array|bool List of mailboxes or hash of options if STATUS/MYRIGHTS response
      *                    is requested, False on error.
      */
     public function listSubscribed($ref, $mailbox, $return_opts = [])
     {
         return $this->_listMailboxes($ref, $mailbox, true, $return_opts, null);
     }
 
     /**
      * IMAP LIST/LSUB command
      *
      * @param string $ref         Reference name
      * @param string $mailbox     Mailbox name
      * @param bool   $subscribed  Enables returning subscribed mailboxes only
      * @param array  $return_opts List of RETURN options (RFC5819: LIST-STATUS, RFC5258: LIST-EXTENDED)
      *                            Possible: MESSAGES, RECENT, UIDNEXT, UIDVALIDITY, UNSEEN,
      *                                      MYRIGHTS, SUBSCRIBED, CHILDREN
      * @param array  $select_opts List of selection options (RFC5258: LIST-EXTENDED)
      *                            Possible: SUBSCRIBED, RECURSIVEMATCH, REMOTE,
      *                                      SPECIAL-USE (RFC6154)
      *
      * @return array|bool List of mailboxes or hash of options if STATUS/MYRIGHTS response
      *                    is requested, False on error.
      */
     protected function _listMailboxes($ref, $mailbox, $subscribed = false, $return_opts = [], $select_opts = [])
     {
         if (!strlen($mailbox)) {
             $mailbox = '*';
         }
 
         $lstatus = false;
         $args    = [];
         $rets    = [];
 
         if (!empty($select_opts) && $this->getCapability('LIST-EXTENDED')) {
             $select_opts = (array) $select_opts;
 
             $args[] = '(' . implode(' ', $select_opts) . ')';
         }
 
         $args[] = $this->escape($ref);
         $args[] = $this->escape($mailbox);
 
         if (!empty($return_opts) && $this->getCapability('LIST-EXTENDED')) {
             $ext_opts    = ['SUBSCRIBED', 'CHILDREN'];
             $rets        = array_intersect($return_opts, $ext_opts);
             $return_opts = array_diff($return_opts, $rets);
         }
 
         if (!empty($return_opts) && $this->getCapability('LIST-STATUS')) {
             $lstatus     = true;
             $status_opts = ['MESSAGES', 'RECENT', 'UIDNEXT', 'UIDVALIDITY', 'UNSEEN', 'SIZE'];
             $opts        = array_diff($return_opts, $status_opts);
             $status_opts = array_diff($return_opts, $opts);
 
             if (!empty($status_opts)) {
                 $rets[] = 'STATUS (' . implode(' ', $status_opts) . ')';
             }
 
             if (!empty($opts)) {
                 $rets = array_merge($rets, $opts);
             }
         }
 
         if (!empty($rets)) {
             $args[] = 'RETURN (' . implode(' ', $rets) . ')';
         }
 
         list($code, $response) = $this->execute($subscribed ? 'LSUB' : 'LIST', $args);
 
         if ($code == self::ERROR_OK) {
             $folders  = [];
             $last     = 0;
             $pos      = 0;
             $response .= "\r\n";
 
             while ($pos = strpos($response, "\r\n", $pos+1)) {
                 // literal string, not real end-of-command-line
                 if ($response[$pos-1] == '}') {
                     continue;
                 }
 
                 $line = substr($response, $last, $pos - $last);
                 $last = $pos + 2;
 
                 if (!preg_match('/^\* (LIST|LSUB|STATUS|MYRIGHTS) /i', $line, $m)) {
                     continue;
                 }
 
                 $cmd  = strtoupper($m[1]);
                 $line = substr($line, strlen($m[0]));
 
                 // * LIST (<options>) <delimiter> <mailbox>
                 if ($cmd == 'LIST' || $cmd == 'LSUB') {
                     list($opts, $delim, $mailbox) = $this->tokenizeResponse($line, 3);
 
                     // Remove redundant separator at the end of folder name, UW-IMAP bug? (#1488879)
                     if ($delim) {
                         $mailbox = rtrim($mailbox, $delim);
                     }
 
                     // Add to result array
                     if (!$lstatus) {
                         $folders[] = $mailbox;
                     }
                     else {
                         $folders[$mailbox] = [];
                     }
 
                     // store folder options
                     if ($cmd == 'LIST') {
                         // Add to options array
                         if (empty($this->data['LIST'][$mailbox])) {
                             $this->data['LIST'][$mailbox] = $opts;
                         }
                         else if (!empty($opts)) {
                             $this->data['LIST'][$mailbox] = array_unique(array_merge(
                                 $this->data['LIST'][$mailbox], $opts));
                         }
                     }
                 }
                 else if ($lstatus) {
                     // * STATUS <mailbox> (<result>)
                     if ($cmd == 'STATUS') {
                         list($mailbox, $status) = $this->tokenizeResponse($line, 2);
 
                         for ($i=0, $len=count($status); $i<$len; $i += 2) {
                             list($name, $value) = $this->tokenizeResponse($status, 2);
                             $folders[$mailbox][$name] = $value;
                         }
                     }
                     // * MYRIGHTS <mailbox> <acl>
                     else if ($cmd == 'MYRIGHTS') {
                         list($mailbox, $acl)  = $this->tokenizeResponse($line, 2);
                         $folders[$mailbox]['MYRIGHTS'] = $acl;
                     }
                 }
             }
 
             return $folders;
         }
 
         return false;
     }
 
     /**
      * Returns count of all messages in a folder
      *
      * @param string $mailbox Mailbox name
      *
      * @return int Number of messages, False on error
      */
     public function countMessages($mailbox)
     {
         if ($this->selected === $mailbox && isset($this->data['EXISTS'])) {
             return $this->data['EXISTS'];
         }
 
         // Check internal cache
         if (!empty($this->data['STATUS:'.$mailbox])) {
             $cache = $this->data['STATUS:'.$mailbox];
             if (isset($cache['MESSAGES'])) {
                 return (int) $cache['MESSAGES'];
             }
         }
 
         // Try STATUS (should be faster than SELECT)
         $counts = $this->status($mailbox);
         if (is_array($counts)) {
             return (int) $counts['MESSAGES'];
         }
 
         return false;
     }
 
     /**
      * Returns count of messages with \Recent flag in a folder
      *
      * @param string $mailbox Mailbox name
      *
      * @return int Number of messages, False on error
      */
     public function countRecent($mailbox)
     {
         if ($this->selected === $mailbox && isset($this->data['RECENT'])) {
             return $this->data['RECENT'];
         }
 
         // Check internal cache
         $cache = $this->data['STATUS:'.$mailbox];
         if (!empty($cache) && isset($cache['RECENT'])) {
             return (int) $cache['RECENT'];
         }
 
         // Try STATUS (should be faster than SELECT)
         $counts = $this->status($mailbox, ['RECENT']);
         if (is_array($counts)) {
             return (int) $counts['RECENT'];
         }
 
         return false;
     }
 
     /**
      * Returns count of messages without \Seen flag in a specified folder
      *
      * @param string $mailbox Mailbox name
      *
      * @return int Number of messages, False on error
      */
     public function countUnseen($mailbox)
     {
         // Check internal cache
         if (!empty($this->data['STATUS:'.$mailbox])) {
             $cache = $this->data['STATUS:'.$mailbox];
             if (isset($cache['UNSEEN'])) {
                 return (int) $cache['UNSEEN'];
             }
         }
 
         // Try STATUS (should be faster than SELECT+SEARCH)
         $counts = $this->status($mailbox);
         if (is_array($counts)) {
             return (int) $counts['UNSEEN'];
         }
 
         // Invoke SEARCH as a fallback
         $index = $this->search($mailbox, 'ALL UNSEEN', false, ['COUNT']);
         if (!$index->is_error()) {
             return $index->count();
         }
 
         return false;
     }
 
     /**
      * Executes ID command (RFC2971)
      *
      * @param array $items Client identification information key/value hash
      *
      * @return array|false Server identification information key/value hash, False on error
      * @since 0.6
      */
     public function id($items = [])
     {
         if (is_array($items) && !empty($items)) {
             foreach ($items as $key => $value) {
                 $args[] = $this->escape($key, true);
                 $args[] = $this->escape($value, true);
             }
         }
 
         list($code, $response) = $this->execute('ID',
             [!empty($args) ? '(' . implode(' ', (array) $args) . ')' : $this->escape(null)],
             0, '/^\* ID /i'
         );
 
         if ($code == self::ERROR_OK && $response) {
             $response = substr($response, 5); // remove prefix "* ID "
             $items    = $this->tokenizeResponse($response, 1);
             $result   = [];
 
             if (is_array($items)) {
                 for ($i=0, $len=count($items); $i<$len; $i += 2) {
                     $result[$items[$i]] = $items[$i+1];
                 }
             }
 
             return $result;
         }
 
         return false;
     }
 
     /**
      * Executes ENABLE command (RFC5161)
      *
      * @param mixed $extension Extension name to enable (or array of names)
      *
      * @return array|bool List of enabled extensions, False on error
      * @since 0.6
      */
     public function enable($extension)
     {
         if (empty($extension)) {
             return false;
         }
 
         if (!$this->hasCapability('ENABLE')) {
             return false;
         }
 
         if (!is_array($extension)) {
             $extension = [$extension];
         }
 
         if (!empty($this->extensions_enabled)) {
             // check if all extensions are already enabled
             $diff = array_diff($extension, $this->extensions_enabled);
 
             if (empty($diff)) {
                 return $extension;
             }
 
             // Make sure the mailbox isn't selected, before enabling extension(s)
             if ($this->selected !== null) {
                 $this->close();
             }
         }
 
         list($code, $response) = $this->execute('ENABLE', $extension, 0, '/^\* ENABLED /i');
 
         if ($code == self::ERROR_OK && $response) {
             $response = substr($response, 10); // remove prefix "* ENABLED "
             $result   = (array) $this->tokenizeResponse($response);
 
             $this->extensions_enabled = array_unique(array_merge((array)$this->extensions_enabled, $result));
 
             return $this->extensions_enabled;
         }
 
         return false;
     }
 
     /**
      * Executes SORT command
      *
      * @param string $mailbox    Mailbox name
      * @param string $field      Field to sort by (ARRIVAL, CC, DATE, FROM, SIZE, SUBJECT, TO)
      * @param string $criteria   Searching criteria
      * @param bool   $return_uid Enables UID SORT usage
      * @param string $encoding   Character set
      *
      * @return rcube_result_index Response data
      */
     public function sort($mailbox, $field = 'ARRIVAL', $criteria = '', $return_uid = false, $encoding = 'US-ASCII')
     {
         $old_sel   = $this->selected;
         $supported = ['ARRIVAL', 'CC', 'DATE', 'FROM', 'SIZE', 'SUBJECT', 'TO'];
         $field     = strtoupper($field);
 
         if ($field == 'INTERNALDATE') {
             $field = 'ARRIVAL';
         }
 
         if (!in_array($field, $supported)) {
             return new rcube_result_index($mailbox);
         }
 
         if (!$this->select($mailbox)) {
             return new rcube_result_index($mailbox);
         }
 
         // return empty result when folder is empty and we're just after SELECT
         if ($old_sel != $mailbox && empty($this->data['EXISTS'])) {
             return new rcube_result_index($mailbox, '* SORT');
         }
 
         // RFC 5957: SORT=DISPLAY
         if (($field == 'FROM' || $field == 'TO') && $this->getCapability('SORT=DISPLAY')) {
             $field = 'DISPLAY' . $field;
         }
 
         $encoding = $encoding ? trim($encoding) : 'US-ASCII';
         $criteria = $criteria ? 'ALL ' . trim($criteria) : 'ALL';
 
         list($code, $response) = $this->execute($return_uid ? 'UID SORT' : 'SORT',
             ["($field)", $encoding, $criteria]);
 
         if ($code != self::ERROR_OK) {
             $response = null;
         }
 
         return new rcube_result_index($mailbox, $response);
     }
 
     /**
      * Executes THREAD command
      *
      * @param string $mailbox    Mailbox name
      * @param string $algorithm  Threading algorithm (ORDEREDSUBJECT, REFERENCES, REFS)
      * @param string $criteria   Searching criteria
      * @param bool   $return_uid Enables UIDs in result instead of sequence numbers
      * @param string $encoding   Character set
      *
      * @return rcube_result_thread Thread data
      */
     public function thread($mailbox, $algorithm = 'REFERENCES', $criteria = '', $return_uid = false, $encoding = 'US-ASCII')
     {
         $old_sel = $this->selected;
 
         if (!$this->select($mailbox)) {
             return new rcube_result_thread($mailbox);
         }
 
         // return empty result when folder is empty and we're just after SELECT
         if ($old_sel != $mailbox && !$this->data['EXISTS']) {
             return new rcube_result_thread($mailbox, '* THREAD');
         }
 
         $encoding  = $encoding ? trim($encoding) : 'US-ASCII';
         $algorithm = $algorithm ? trim($algorithm) : 'REFERENCES';
         $criteria  = $criteria ? 'ALL '.trim($criteria) : 'ALL';
 
         list($code, $response) = $this->execute($return_uid ? 'UID THREAD' : 'THREAD',
             [$algorithm, $encoding, $criteria]);
 
         if ($code != self::ERROR_OK) {
             $response = null;
         }
 
         return new rcube_result_thread($mailbox, $response);
     }
 
     /**
      * Executes SEARCH command
      *
      * @param string $mailbox    Mailbox name
      * @param string $criteria   Searching criteria
      * @param bool   $return_uid Enable UID in result instead of sequence ID
      * @param array  $items      Return items (MIN, MAX, COUNT, ALL)
      *
      * @return rcube_result_index Result data
      */
     public function search($mailbox, $criteria, $return_uid = false, $items = [])
     {
         $old_sel = $this->selected;
 
         if (!$this->select($mailbox)) {
             return new rcube_result_index($mailbox);
         }
 
         // return empty result when folder is empty and we're just after SELECT
         if ($old_sel != $mailbox && !$this->data['EXISTS']) {
             return new rcube_result_index($mailbox, '* SEARCH');
         }
 
         // If ESEARCH is supported always use ALL
         // but not when items are specified or using simple id2uid search
         if (empty($items) && preg_match('/[^0-9]/', $criteria)) {
             $items = ['ALL'];
         }
 
         $esearch  = empty($items) ? false : $this->getCapability('ESEARCH');
         $criteria = trim($criteria);
         $params   = '';
 
         // RFC4731: ESEARCH
         if (!empty($items) && $esearch) {
             $params .= 'RETURN (' . implode(' ', $items) . ')';
         }
 
         if (!empty($criteria)) {
             $params .= ($params ? ' ' : '') . $criteria;
         }
         else {
             $params .= 'ALL';
         }
 
         list($code, $response) = $this->execute($return_uid ? 'UID SEARCH' : 'SEARCH', [$params]);
 
         if ($code != self::ERROR_OK) {
             $response = null;
         }
 
         return new rcube_result_index($mailbox, $response);
     }
 
     /**
      * Simulates SORT command by using FETCH and sorting.
      *
      * @param string       $mailbox      Mailbox name
      * @param string|array $message_set  Searching criteria (list of messages to return)
      * @param string       $index_field  Field to sort by (ARRIVAL, CC, DATE, FROM, SIZE, SUBJECT, TO)
      * @param bool         $skip_deleted Makes that DELETED messages will be skipped
      * @param bool         $uidfetch     Enables UID FETCH usage
      * @param bool         $return_uid   Enables returning UIDs instead of IDs
      *
      * @return rcube_result_index Response data
      */
     public function index($mailbox, $message_set, $index_field = '', $skip_deleted = true,
         $uidfetch = false, $return_uid = false)
     {
         $msg_index = $this->fetchHeaderIndex($mailbox, $message_set,
             $index_field, $skip_deleted, $uidfetch, $return_uid);
 
         if (!empty($msg_index)) {
             asort($msg_index); // ASC
             $msg_index = array_keys($msg_index);
             $msg_index = '* SEARCH ' . implode(' ', $msg_index);
         }
         else {
             $msg_index = is_array($msg_index) ? '* SEARCH' : null;
         }
 
         return new rcube_result_index($mailbox, $msg_index);
     }
 
     /**
      * Fetches specified header/data value for a set of messages.
      *
      * @param string       $mailbox      Mailbox name
      * @param string|array $message_set  Searching criteria (list of messages to return)
      * @param string       $index_field  Field to sort by (ARRIVAL, CC, DATE, FROM, SIZE, SUBJECT, TO)
      * @param bool         $skip_deleted Makes that DELETED messages will be skipped
      * @param bool         $uidfetch     Enables UID FETCH usage
      * @param bool         $return_uid   Enables returning UIDs instead of IDs
      *
      * @return array|bool List of header values or False on failure
      */
     public function fetchHeaderIndex($mailbox, $message_set, $index_field = '', $skip_deleted = true,
         $uidfetch = false, $return_uid = false)
     {
         // Validate input
         if (is_array($message_set)) {
             if (!($message_set = $this->compressMessageSet($message_set))) {
                 return false;
             }
         }
         else if (empty($message_set)) {
             return false;
         }
         else if (strpos($message_set, ':')) {
             list($from_idx, $to_idx) = explode(':', $message_set);
             if ($to_idx != '*' && (int) $from_idx > (int) $to_idx) {
                 return false;
             }
         }
 
         $index_field = empty($index_field) ? 'DATE' : strtoupper($index_field);
 
         $supported = [
             'DATE'         => 1,
             'INTERNALDATE' => 4,
             'ARRIVAL'      => 4,
             'FROM'         => 1,
             'REPLY-TO'     => 1,
             'SENDER'       => 1,
             'TO'           => 1,
             'CC'           => 1,
             'SUBJECT'      => 1,
             'UID'          => 2,
             'SIZE'         => 2,
             'SEEN'         => 3,
             'RECENT'       => 3,
             'DELETED'      => 3,
         ];
 
         if (empty($supported[$index_field])) {
             return false;
         }
 
         $mode = $supported[$index_field];
 
         //  Select the mailbox
         if (!$this->select($mailbox)) {
             return false;
         }
 
         // build FETCH command string
         $key    = $this->nextTag();
         $cmd    = $uidfetch ? 'UID FETCH' : 'FETCH';
         $fields = [];
 
         if ($return_uid) {
             $fields[] = 'UID';
         }
         if ($skip_deleted) {
             $fields[] = 'FLAGS';
         }
 
         if ($mode == 1) {
             if ($index_field == 'DATE') {
                 $fields[] = 'INTERNALDATE';
             }
             $fields[] = "BODY.PEEK[HEADER.FIELDS ($index_field)]";
         }
         else if ($mode == 2) {
             if ($index_field == 'SIZE') {
                 $fields[] = 'RFC822.SIZE';
             }
             else if (!$return_uid || $index_field != 'UID') {
                 $fields[] = $index_field;
             }
         }
         else if ($mode == 3 && !$skip_deleted) {
             $fields[] = 'FLAGS';
         }
         else if ($mode == 4) {
             $fields[] = 'INTERNALDATE';
         }
 
         $request = "$key $cmd $message_set (" . implode(' ', $fields) . ")";
 
         if (!$this->putLine($request)) {
             $this->setError(self::ERROR_COMMAND, "Failed to send $cmd command");
             return false;
         }
 
         $result = [];
 
         do {
             $line = rtrim($this->readLine(200));
             $line = $this->multLine($line);
 
             if (preg_match('/^\* ([0-9]+) FETCH/', $line, $m)) {
                 $id     = $m[1];
                 $flags  = null;
 
                 if ($return_uid) {
                     if (preg_match('/UID ([0-9]+)/', $line, $matches)) {
                         $id = (int) $matches[1];
                     }
                     else {
                         continue;
                     }
                 }
 
                 if ($skip_deleted && preg_match('/FLAGS \(([^)]+)\)/', $line, $matches)) {
                     $flags = explode(' ', strtoupper($matches[1]));
                     if (in_array('\\DELETED', $flags)) {
                         continue;
                     }
                 }
 
                 if ($mode == 1 && $index_field == 'DATE') {
                     if (preg_match('/BODY\[HEADER\.FIELDS \("*DATE"*\)\] (.*)/', $line, $matches)) {
                         $value = preg_replace(['/^"*[a-z]+:/i'], '', $matches[1]);
                         $value = trim($value);
                         $result[$id] = rcube_utils::strtotime($value);
                     }
                     // non-existent/empty Date: header, use INTERNALDATE
                     if (empty($result[$id])) {
                         if (preg_match('/INTERNALDATE "([^"]+)"/', $line, $matches)) {
                             $result[$id] = rcube_utils::strtotime($matches[1]);
                         }
                         else {
                             $result[$id] = 0;
                         }
                     }
                 }
                 else if ($mode == 1) {
                     if (preg_match('/BODY\[HEADER\.FIELDS \("?(FROM|REPLY-TO|SENDER|TO|SUBJECT)"?\)\] (.*)/', $line, $matches)) {
                         $value = preg_replace(['/^"*[a-z]+:/i', '/\s+$/sm'], ['', ''], $matches[2]);
                         $result[$id] = trim($value);
                     }
                     else {
                         $result[$id] = '';
                     }
                 }
                 else if ($mode == 2) {
                     if (preg_match('/' . $index_field . ' ([0-9]+)/', $line, $matches)) {
                         $result[$id] = trim($matches[1]);
                     }
                     else {
                         $result[$id] = 0;
                     }
                 }
                 else if ($mode == 3) {
                     if (!$flags && preg_match('/FLAGS \(([^)]+)\)/', $line, $matches)) {
                         $flags = explode(' ', $matches[1]);
                     }
                     $result[$id] = in_array("\\".$index_field, (array) $flags) ? 1 : 0;
                 }
                 else if ($mode == 4) {
                     if (preg_match('/INTERNALDATE "([^"]+)"/', $line, $matches)) {
                         $result[$id] = rcube_utils::strtotime($matches[1]);
                     }
                     else {
                         $result[$id] = 0;
                     }
                 }
             }
         }
         while (!$this->startsWith($line, $key, true, true));
 
         return $result;
     }
 
     /**
      * Returns message sequence identifier
      *
      * @param string $mailbox Mailbox name
      * @param int    $uid     Message unique identifier (UID)
      *
      * @return int Message sequence identifier
      */
     public function UID2ID($mailbox, $uid)
     {
         if ($uid > 0) {
             $index = $this->search($mailbox, "UID $uid");
 
             if ($index->count() == 1) {
                 $arr = $index->get();
                 return (int) $arr[0];
             }
         }
     }
 
     /**
      * Returns message unique identifier (UID)
      *
      * @param string $mailbox Mailbox name
      * @param int    $uid     Message sequence identifier
      *
      * @return int Message unique identifier
      */
     public function ID2UID($mailbox, $id)
     {
         if (empty($id) || $id < 0) {
             return null;
         }
 
         if (!$this->select($mailbox)) {
             return null;
         }
 
         if (!empty($this->data['UID-MAP'][$id])) {
             return $this->data['UID-MAP'][$id];
         }
 
         if (isset($this->data['EXISTS']) && $id > $this->data['EXISTS']) {
             return null;
         }
 
         $index = $this->search($mailbox, $id, true);
 
         if ($index->count() == 1) {
             $arr = $index->get();
             return $this->data['UID-MAP'][$id] = (int) $arr[0];
         }
     }
 
     /**
      * Sets flag of the message(s)
      *
      * @param string       $mailbox  Mailbox name
      * @param string|array $messages Message UID(s)
      * @param string       $flag     Flag name
      *
      * @return bool True on success, False on failure
      */
     public function flag($mailbox, $messages, $flag)
     {
         return $this->modFlag($mailbox, $messages, $flag, '+');
     }
 
     /**
      * Unsets flag of the message(s)
      *
      * @param string       $mailbox  Mailbox name
      * @param string|array $messages Message UID(s)
      * @param string       $flag     Flag name
      *
      * @return bool True on success, False on failure
      */
     public function unflag($mailbox, $messages, $flag)
     {
         return $this->modFlag($mailbox, $messages, $flag, '-');
     }
 
     /**
      * Changes flag of the message(s)
      *
      * @param string       $mailbox  Mailbox name
      * @param string|array $messages Message UID(s)
      * @param string       $flag     Flag name
      * @param string       $mod      Modifier [+|-]. Default: "+".
      *
      * @return bool True on success, False on failure
      */
     protected function modFlag($mailbox, $messages, $flag, $mod = '+')
     {
         if (!$flag) {
             return false;
         }
 
         if (!$this->select($mailbox)) {
             return false;
         }
 
         if (empty($this->data['READ-WRITE'])) {
             $this->setError(self::ERROR_READONLY, "Mailbox is read-only");
             return false;
         }
 
         if (!empty($this->flags[strtoupper($flag)])) {
             $flag = $this->flags[strtoupper($flag)];
         }
 
         // if PERMANENTFLAGS is not specified all flags are allowed
         if (!empty($this->data['PERMANENTFLAGS'])
             && !in_array($flag, (array) $this->data['PERMANENTFLAGS'])
             && !in_array('\\*', (array) $this->data['PERMANENTFLAGS'])
         ) {
             return false;
         }
 
         // Clear internal status cache
         if ($flag == 'SEEN') {
             unset($this->data['STATUS:'.$mailbox]['UNSEEN']);
         }
 
         if ($mod != '+' && $mod != '-') {
             $mod = '+';
         }
 
         $result = $this->execute('UID STORE',
             [$this->compressMessageSet($messages), $mod . 'FLAGS.SILENT', "($flag)"],
             self::COMMAND_NORESPONSE
         );
 
         return $result == self::ERROR_OK;
     }
 
     /**
      * Copies message(s) from one folder to another
      *
      * @param string|array $messages Message UID(s)
      * @param string       $from     Mailbox name
      * @param string       $to       Destination mailbox name
      *
      * @return bool True on success, False on failure
      */
     public function copy($messages, $from, $to)
     {
         // Clear last COPYUID data
         unset($this->data['COPYUID']);
 
         if (!$this->select($from)) {
             return false;
         }
 
         // Clear internal status cache
         unset($this->data['STATUS:'.$to]);
 
         $result = $this->execute('UID COPY',
             [$this->compressMessageSet($messages), $this->escape($to)],
             self::COMMAND_NORESPONSE
         );
 
         return $result == self::ERROR_OK;
     }
 
     /**
      * Moves message(s) from one folder to another.
      *
      * @param string|array $messages Message UID(s)
      * @param string       $from     Mailbox name
      * @param string       $to       Destination mailbox name
      *
      * @return bool True on success, False on failure
      */
     public function move($messages, $from, $to)
     {
         if (!$this->select($from)) {
             return false;
         }
 
         if (empty($this->data['READ-WRITE'])) {
             $this->setError(self::ERROR_READONLY, "Mailbox is read-only");
             return false;
         }
 
         // use MOVE command (RFC 6851)
         if ($this->hasCapability('MOVE')) {
             // Clear last COPYUID data
             unset($this->data['COPYUID']);
 
             // Clear internal status cache
             unset($this->data['STATUS:'.$to]);
             $this->clear_status_cache($from);
 
             $result = $this->execute('UID MOVE',
                 [$this->compressMessageSet($messages), $this->escape($to)],
                 self::COMMAND_NORESPONSE
             );
 
             return $result == self::ERROR_OK;
         }
 
         // use COPY + STORE +FLAGS.SILENT \Deleted + EXPUNGE
         $result = $this->copy($messages, $from, $to);
 
         if ($result) {
             // Clear internal status cache
             unset($this->data['STATUS:'.$from]);
 
             $result = $this->flag($from, $messages, 'DELETED');
 
             if ($messages == '*') {
                 // CLOSE+SELECT should be faster than EXPUNGE
                 $this->close();
             }
             else {
                 $this->expunge($from, $messages);
             }
         }
 
         return $result;
     }
 
     /**
      * FETCH command (RFC3501)
      *
      * @param string $mailbox     Mailbox name
      * @param mixed  $message_set Message(s) sequence identifier(s) or UID(s)
      * @param bool   $is_uid      True if $message_set contains UIDs
      * @param array  $query_items FETCH command data items
      * @param string $mod_seq     Modification sequence for CHANGEDSINCE (RFC4551) query
      * @param bool   $vanished    Enables VANISHED parameter (RFC5162) for CHANGEDSINCE query
      *
      * @return array List of rcube_message_header elements, False on error
      * @since 0.6
      */
     public function fetch($mailbox, $message_set, $is_uid = false, $query_items = [],
         $mod_seq = null, $vanished = false)
     {
         if (!$this->select($mailbox)) {
             return false;
         }
 
         $message_set = $this->compressMessageSet($message_set);
         $result      = [];
 
         $key      = $this->nextTag();
         $cmd      = ($is_uid ? 'UID ' : '') . 'FETCH';
         $request  = "$key $cmd $message_set (" . implode(' ', $query_items) . ")";
 
         if ($mod_seq !== null && $this->hasCapability('CONDSTORE')) {
             $request .= " (CHANGEDSINCE $mod_seq" . ($vanished ? " VANISHED" : '') .")";
         }
 
         if (!$this->putLine($request)) {
             $this->setError(self::ERROR_COMMAND, "Failed to send $cmd command");
             return false;
         }
 
         do {
             $line = $this->readFullLine(4096);
 
             if (!$line) {
                 break;
             }
 
             // Sample reply line:
             // * 321 FETCH (UID 2417 RFC822.SIZE 2730 FLAGS (\Seen)
             // INTERNALDATE "16-Nov-2008 21:08:46 +0100" BODYSTRUCTURE (...)
             // BODY[HEADER.FIELDS ...
 
             if (preg_match('/^\* ([0-9]+) FETCH/', $line, $m)) {
                 $id = intval($m[1]);
 
                 $result[$id]            = new rcube_message_header;
                 $result[$id]->id        = $id;
                 $result[$id]->subject   = '';
                 $result[$id]->messageID = 'mid:' . $id;
 
                 $headers = null;
                 $lines   = [];
                 $line    = substr($line, strlen($m[0]) + 2);
                 $ln      = 0;
 
                 // Tokenize response and assign to object properties
                 while (($tokens = $this->tokenizeResponse($line, 2)) && count($tokens) == 2) {
                     list($name, $value) = $tokens;
                     if ($name == 'UID') {
                         $result[$id]->uid = intval($value);
                     }
                     else if ($name == 'RFC822.SIZE') {
                         $result[$id]->size = intval($value);
                     }
                     else if ($name == 'RFC822.TEXT') {
                         $result[$id]->body = $value;
                     }
                     else if ($name == 'INTERNALDATE') {
                         $result[$id]->internaldate = $value;
                         $result[$id]->date         = $value;
                         $result[$id]->timestamp    = rcube_utils::strtotime($value);
                     }
                     else if ($name == 'FLAGS') {
                         if (!empty($value)) {
                             foreach ((array)$value as $flag) {
                                 $flag = str_replace(['$', "\\"], '', $flag);
                                 $flag = strtoupper($flag);
 
                                 $result[$id]->flags[$flag] = true;
                             }
                         }
                     }
                     else if ($name == 'MODSEQ') {
                         $result[$id]->modseq = $value[0];
                     }
                     else if ($name == 'ENVELOPE') {
                         $result[$id]->envelope = $value;
                     }
                     else if ($name == 'BODYSTRUCTURE' || ($name == 'BODY' && count($value) > 2)) {
                         if (!is_array($value[0]) && (strtolower($value[0]) == 'message' && strtolower($value[1]) == 'rfc822')) {
                             $value = [$value];
                         }
                         $result[$id]->bodystructure = $value;
                     }
                     else if ($name == 'RFC822') {
                         $result[$id]->body = $value;
                     }
                     else if (stripos($name, 'BODY[') === 0) {
                         $name = str_replace(']', '', substr($name, 5));
 
                         if ($name == 'HEADER.FIELDS') {
                             // skip ']' after headers list
                             $this->tokenizeResponse($line, 1);
                             $headers = $this->tokenizeResponse($line, 1);
                         }
                         else if (strlen($name)) {
                             $result[$id]->bodypart[$name] = $value;
                         }
                         else {
                             $result[$id]->body = $value;
                         }
                     }
                 }
 
                 // create array with header field:data
                 if (!empty($headers)) {
                     $headers = explode("\n", trim($headers));
                     foreach ($headers as $resln) {
                         if (ord($resln[0]) <= 32) {
                             $lines[$ln] .= (empty($lines[$ln]) ? '' : "\n") . trim($resln);
                         }
                         else {
                             $lines[++$ln] = trim($resln);
                         }
                     }
 
                     foreach ($lines as $str) {
                         list($field, $string) = explode(':', $str, 2);
 
                         $field  = strtolower($field);
                         $string = preg_replace('/\n[\t\s]*/', ' ', trim($string));
 
                         switch ($field) {
                         case 'date';
                             $string                 = substr($string, 0, 128);
                             $result[$id]->date      = $string;
                             $result[$id]->timestamp = rcube_utils::strtotime($string);
                             break;
                         case 'to':
                             $result[$id]->to = preg_replace('/undisclosed-recipients:[;,]*/', '', $string);
                             break;
                         case 'from':
                         case 'subject':
                             $string = substr($string, 0, 2048);
                         case 'cc':
                         case 'bcc':
                         case 'references':
                             $result[$id]->{$field} = $string;
                             break;
                         case 'reply-to':
                             $result[$id]->replyto = $string;
                             break;
                         case 'content-transfer-encoding':
                             $result[$id]->encoding = substr($string, 0, 32);
                         break;
                         case 'content-type':
                             $ctype_parts = preg_split('/[; ]+/', $string);
                             $result[$id]->ctype = strtolower(array_first($ctype_parts));
                             if (preg_match('/charset\s*=\s*"?([a-z0-9\-\.\_]+)"?/i', $string, $regs)) {
                                 $result[$id]->charset = $regs[1];
                             }
                             break;
                         case 'in-reply-to':
                             $result[$id]->in_reply_to = str_replace(["\n", '<', '>'], '', $string);
                             break;
                         case 'disposition-notification-to':
                         case 'x-confirm-reading-to':
                             $result[$id]->mdn_to = substr($string, 0, 2048);
                             break;
                         case 'message-id':
                             $result[$id]->messageID = substr($string, 0, 2048);
                             break;
                         case 'x-priority':
                             if (preg_match('/^(\d+)/', $string, $matches)) {
                                 $result[$id]->priority = intval($matches[1]);
                             }
                             break;
                         default:
                             if (strlen($field) < 3) {
                                 break;
                             }
                             if (!empty($result[$id]->others[$field])) {
                                 $string = array_merge((array) $result[$id]->others[$field], (array) $string);
                             }
                             $result[$id]->others[$field] = $string;
                         }
                     }
                 }
             }
             // VANISHED response (QRESYNC RFC5162)
             // Sample: * VANISHED (EARLIER) 300:310,405,411
             else if (preg_match('/^\* VANISHED [()EARLIER]*/i', $line, $match)) {
                 $line   = substr($line, strlen($match[0]));
                 $v_data = $this->tokenizeResponse($line, 1);
 
                 $this->data['VANISHED'] = $v_data;
             }
         }
         while (!$this->startsWith($line, $key, true));
 
         return $result;
     }
 
     /**
      * Returns message(s) data (flags, headers, etc.)
      *
      * @param string $mailbox     Mailbox name
      * @param mixed  $message_set Message(s) sequence identifier(s) or UID(s)
      * @param bool   $is_uid      True if $message_set contains UIDs
      * @param bool   $bodystr     Enable to add BODYSTRUCTURE data to the result
      * @param array  $add_headers List of additional headers
      *
      * @return bool|array List of rcube_message_header elements, False on error
      */
     public function fetchHeaders($mailbox, $message_set, $is_uid = false, $bodystr = false, $add_headers = [])
     {
         $query_items = ['UID', 'RFC822.SIZE', 'FLAGS', 'INTERNALDATE'];
         $headers     = ['DATE', 'FROM', 'TO', 'SUBJECT', 'CONTENT-TYPE', 'CC', 'REPLY-TO',
             'LIST-POST', 'DISPOSITION-NOTIFICATION-TO', 'X-PRIORITY'];
 
         if (!empty($add_headers)) {
             $add_headers = array_map('strtoupper', $add_headers);
             $headers     = array_unique(array_merge($headers, $add_headers));
         }
 
         if ($bodystr) {
             $query_items[] = 'BODYSTRUCTURE';
         }
 
         $query_items[] = 'BODY.PEEK[HEADER.FIELDS (' . implode(' ', $headers) . ')]';
 
         return $this->fetch($mailbox, $message_set, $is_uid, $query_items);
     }
 
     /**
      * Returns message data (flags, headers, etc.)
      *
      * @param string $mailbox     Mailbox name
      * @param int    $id          Message sequence identifier or UID
      * @param bool   $is_uid      True if $id is an UID
      * @param bool   $bodystr     Enable to add BODYSTRUCTURE data to the result
      * @param array  $add_headers List of additional headers
      *
      * @return bool|rcube_message_header Message data, False on error
      */
     public function fetchHeader($mailbox, $id, $is_uid = false, $bodystr = false, $add_headers = [])
     {
         $a = $this->fetchHeaders($mailbox, $id, $is_uid, $bodystr, $add_headers);
 
         if (is_array($a)) {
             return array_first($a);
         }
 
         return false;
     }
 
     /**
      * Sort messages by specified header field
      *
      * @param array  $messages Array of rcube_message_header objects
      * @param string $field    Name of the property to sort by
      * @param string $order    Sorting order (ASC|DESC)
      *
      * @return array Sorted input array
      */
     public static function sortHeaders($messages, $field, $order = 'ASC')
     {
         $field = empty($field) ? 'uid' : strtolower($field);
         $order = empty($order) ? 'ASC' : strtoupper($order);
         $index = [];
 
         reset($messages);
 
         // Create an index
         foreach ($messages as $key => $headers) {
             switch ($field) {
             case 'arrival':
                 $field = 'internaldate';
                 // no-break
             case 'date':
             case 'internaldate':
             case 'timestamp':
                 $value = rcube_utils::strtotime($headers->$field);
                 if (!$value && $field != 'timestamp') {
                     $value = $headers->timestamp;
                 }
 
                 break;
 
             default:
                 // @TODO: decode header value, convert to UTF-8
                 $value = $headers->$field;
                 if (is_string($value)) {
                     $value = str_replace('"', '', $value);
 
                     if ($field == 'subject') {
                         $value = rcube_utils::remove_subject_prefix($value);
                     }
                 }
             }
 
             $index[$key] = $value;
         }
 
         $sort_order = $order == 'ASC' ? SORT_ASC : SORT_DESC;
         $sort_flags = SORT_STRING | SORT_FLAG_CASE;
 
         if (in_array($field, ['arrival', 'date', 'internaldate', 'timestamp'])) {
             $sort_flags = SORT_NUMERIC;
         }
 
         array_multisort($index, $sort_order, $sort_flags, $messages);
 
         return $messages;
     }
 
     /**
      * Fetch MIME headers of specified message parts
      *
      * @param string $mailbox Mailbox name
      * @param int    $uid     Message UID
      * @param array  $parts   Message part identifiers
      * @param bool   $mime    Use MIME instead of HEADER
      *
      * @return array|bool Array containing headers string for each specified body
      *                    False on failure.
      */
     public function fetchMIMEHeaders($mailbox, $uid, $parts, $mime = true)
     {
         if (!$this->select($mailbox)) {
             return false;
         }
 
         $result = false;
         $parts  = (array) $parts;
         $key    = $this->nextTag();
         $peeks  = [];
         $type   = $mime ? 'MIME' : 'HEADER';
 
         // format request
         foreach ($parts as $part) {
             $peeks[] = "BODY.PEEK[$part.$type]";
         }
 
         $request = "$key UID FETCH $uid (" . implode(' ', $peeks) . ')';
 
         // send request
         if (!$this->putLine($request)) {
             $this->setError(self::ERROR_COMMAND, "Failed to send UID FETCH command");
             return false;
         }
 
         do {
             $line = $this->readLine(1024);
             if (preg_match('/^\* [0-9]+ FETCH [0-9UID( ]+/', $line, $m)) {
                 $line = ltrim(substr($line, strlen($m[0])));
                 while (preg_match('/^\s*BODY\[([0-9\.]+)\.'.$type.'\]/', $line, $matches)) {
                     $line = substr($line, strlen($matches[0]));
                     $result[$matches[1]] = trim($this->multLine($line));
                     $line = $this->readLine(1024);
                 }
             }
         }
         while (!$this->startsWith($line, $key, true));
 
         return $result;
     }
 
     /**
      * Fetches message part header
      */
     public function fetchPartHeader($mailbox, $id, $is_uid = false, $part = null)
     {
         $part = empty($part) ? 'HEADER' : $part.'.MIME';
 
         return $this->handlePartBody($mailbox, $id, $is_uid, $part);
     }
 
     /**
      * Fetches body of the specified message part
      */
     public function handlePartBody($mailbox, $id, $is_uid = false, $part = '', $encoding = null, $print = null,
         $file = null, $formatted = false, $max_bytes = 0)
     {
         if (!$this->select($mailbox)) {
             return false;
         }
 
         $binary    = true;
         $initiated = false;
 
         do {
             if (!$initiated) {
                 switch ($encoding) {
                 case 'base64':
                     $mode = 1;
                     break;
                 case 'quoted-printable':
                     $mode = 2;
                     break;
                 case 'x-uuencode':
                 case 'x-uue':
                 case 'uue':
                 case 'uuencode':
                     $mode = 3;
                     break;
                 default:
                     $mode = 0;
                 }
 
                 // Use BINARY extension when possible (and safe)
                 $binary     = $binary && $mode && preg_match('/^[0-9.]+$/', $part) && $this->hasCapability('BINARY');
                 $fetch_mode = $binary ? 'BINARY' : 'BODY';
                 $partial    = $max_bytes ? sprintf('<0.%d>', $max_bytes) : '';
 
                 // format request
                 $key       = $this->nextTag();
                 $cmd       = ($is_uid ? 'UID ' : '') . 'FETCH';
                 $request   = "$key $cmd $id ($fetch_mode.PEEK[$part]$partial)";
                 $result    = false;
                 $found     = false;
                 $initiated = true;
 
                 // send request
                 if (!$this->putLine($request)) {
                     $this->setError(self::ERROR_COMMAND, "Failed to send $cmd command");
                     return false;
                 }
 
                 if ($binary) {
                     // WARNING: Use $formatted argument with care, this may break binary data stream
                     $mode = -1;
                 }
             }
 
             $line = trim($this->readLine(1024));
 
             if (!$line) {
                 break;
             }
 
             // handle UNKNOWN-CTE response - RFC 3516, try again with standard BODY request
             if ($binary && !$found && preg_match('/^' . $key . ' NO \[(UNKNOWN-CTE|PARSE)\]/i', $line)) {
                 $binary = $initiated = false;
                 continue;
             }
 
             // skip irrelevant untagged responses (we have a result already)
             if ($found || !preg_match('/^\* ([0-9]+) FETCH (.*)$/', $line, $m)) {
                 continue;
             }
 
             $line = $m[2];
 
             // handle one line response
             if ($line[0] == '(' && substr($line, -1) == ')') {
                 // tokenize content inside brackets
                 // the content can be e.g.: (UID 9844 BODY[2.4] NIL)
                 $tokens = $this->tokenizeResponse(preg_replace('/(^\(|\)$)/', '', $line));
 
                 for ($i=0; $i<count($tokens); $i+=2) {
                     if (preg_match('/^(BODY|BINARY)/i', $tokens[$i])) {
                         $result = $tokens[$i+1];
                         $found  = true;
                         break;
                     }
                 }
 
                 if ($result !== false) {
                     if ($mode == 1) {
                         $result = base64_decode($result);
                     }
                     else if ($mode == 2) {
                         $result = quoted_printable_decode($result);
                     }
                     else if ($mode == 3) {
                         $result = convert_uudecode($result);
                     }
                 }
             }
             // response with string literal
             else if (preg_match('/\{([0-9]+)\}$/', $line, $m)) {
                 $bytes = (int) $m[1];
                 $prev  = '';
                 $found = true;
+                $chunkSize = 1024 * 1024;
 
                 // empty body
                 if (!$bytes) {
                     $result = '';
                 }
                 else while ($bytes > 0) {
-                    $line = $this->readLine(8192);
+                    $line = $this->readBytes($bytes > $chunkSize ? $chunkSize : $bytes);
 
-                    if ($line === null) {
+                    if ($line === '') {
                         break;
                     }
 
                     $len = strlen($line);
 
                     if ($len > $bytes) {
                         $line = substr($line, 0, $bytes);
                         $len  = strlen($line);
                     }
                     $bytes -= $len;
 
                     // BASE64
                     if ($mode == 1) {
                         $line = preg_replace('|[^a-zA-Z0-9+=/]|', '', $line);
                         // create chunks with proper length for base64 decoding
                         $line = $prev.$line;
                         $length = strlen($line);
                         if ($length % 4) {
                             $length = floor($length / 4) * 4;
                             $prev = substr($line, $length);
                             $line = substr($line, 0, $length);
                         }
                         else {
                             $prev = '';
                         }
                         $line = base64_decode($line);
                     }
                     // QUOTED-PRINTABLE
                     else if ($mode == 2) {
                         $line = rtrim($line, "\t\r\0\x0B");
                         $line = quoted_printable_decode($line);
                     }
                     // UUENCODE
                     else if ($mode == 3) {
                         $line = rtrim($line, "\t\r\n\0\x0B");
                         if ($line == 'end' || preg_match('/^begin\s+[0-7]+\s+.+$/', $line)) {
                             continue;
                         }
                         $line = convert_uudecode($line);
                     }
                     // default
                     else if ($formatted) {
                         $line = rtrim($line, "\t\r\n\0\x0B") . "\n";
                     }
 
                     if ($file) {
                         if (fwrite($file, $line) === false) {
                             break;
                         }
                     }
                     else if ($print) {
                         echo $line;
                     }
                     else {
                         $result .= $line;
                     }
                 }
             }
         }
         while (!$this->startsWith($line, $key, true) || !$initiated);
 
         if ($result !== false) {
             if ($file) {
                 return fwrite($file, $result);
             }
             else if ($print) {
                 echo $result;
                 return true;
             }
 
             return $result;
         }
 
         return false;
     }
 
     /**
      * Handler for IMAP APPEND command
      *
      * @param string       $mailbox Mailbox name
      * @param string|array $message The message source string or array (of strings and file pointers)
      * @param array        $flags   Message flags
      * @param string       $date    Message internal date
      * @param bool         $binary  Enable BINARY append (RFC3516)
      *
      * @return string|bool On success APPENDUID response (if available) or True, False on failure
      */
     public function append($mailbox, &$message, $flags = [], $date = null, $binary = false)
     {
         unset($this->data['APPENDUID']);
 
         if ($mailbox === null || $mailbox === '') {
             return false;
         }
 
         $binary       = $binary && $this->getCapability('BINARY');
         $literal_plus = !$binary && !empty($this->prefs['literal+']);
         $len          = 0;
         $msg          = is_array($message) ? $message : [&$message];
         $chunk_size   = 512000;
 
         for ($i=0, $cnt=count($msg); $i<$cnt; $i++) {
             if (is_resource($msg[$i])) {
                 $stat = fstat($msg[$i]);
                 if ($stat === false) {
                     return false;
                 }
                 $len += $stat['size'];
             }
             else {
                 if (!$binary) {
                     $msg[$i] = str_replace("\r", '', $msg[$i]);
                     $msg[$i] = str_replace("\n", "\r\n", $msg[$i]);
                 }
 
                 $len += strlen($msg[$i]);
             }
         }
 
         if (!$len) {
             return false;
         }
 
         // build APPEND command
         $key = $this->nextTag();
         $request = "$key APPEND " . $this->escape($mailbox) . ' (' . $this->flagsToStr($flags) . ')';
         if (!empty($date)) {
             $request .= ' ' . $this->escape($date);
         }
         $request .= ' ' . ($binary ? '~' : '') . '{' . $len . ($literal_plus ? '+' : '') . '}';
 
         // send APPEND command
         if (!$this->putLine($request)) {
             $this->setError(self::ERROR_COMMAND, "Failed to send APPEND command");
             return false;
         }
 
         // Do not wait when LITERAL+ is supported
         if (!$literal_plus) {
             $line = $this->readReply();
 
             if ($line[0] != '+') {
                 $this->parseResult($line, 'APPEND: ');
                 return false;
             }
         }
 
         foreach ($msg as $msg_part) {
             // file pointer
             if (is_resource($msg_part)) {
                 rewind($msg_part);
                 while (!feof($msg_part) && $this->fp) {
                     $buffer = fread($msg_part, $chunk_size);
                     $this->putLine($buffer, false);
                 }
                 fclose($msg_part);
             }
             // string
             else {
                 $size = strlen($msg_part);
 
                 // Break up the data by sending one chunk (up to 512k) at a time.
                 // This approach reduces our peak memory usage
                 for ($offset = 0; $offset < $size; $offset += $chunk_size) {
                     $chunk = substr($msg_part, $offset, $chunk_size);
                     if (!$this->putLine($chunk, false)) {
                         return false;
                     }
                 }
             }
         }
 
         if (!$this->putLine('')) { // \r\n
             return false;
         }
 
         do {
             $line = $this->readLine();
         } while (!$this->startsWith($line, $key, true, true));
 
         // Clear internal status cache
         unset($this->data['STATUS:'.$mailbox]);
 
         if ($this->parseResult($line, 'APPEND: ') != self::ERROR_OK) {
             return false;
         }
 
         if (!empty($this->data['APPENDUID'])) {
             return $this->data['APPENDUID'];
         }
 
         return true;
     }
 
     /**
      * Handler for IMAP APPEND command.
      *
      * @param string $mailbox Mailbox name
      * @param string $path    Path to the file with message body
      * @param string $headers Message headers
      * @param array  $flags   Message flags
      * @param string $date    Message internal date
      * @param bool   $binary  Enable BINARY append (RFC3516)
      *
      * @return string|bool On success APPENDUID response (if available) or True, False on failure
      */
     public function appendFromFile($mailbox, $path, $headers = null, $flags = [], $date = null, $binary = false)
     {
         // open message file
         if (file_exists(realpath($path))) {
             $fp = fopen($path, 'r');
         }
 
         if (empty($fp)) {
             $this->setError(self::ERROR_UNKNOWN, "Couldn't open $path for reading");
             return false;
         }
 
         $message = [];
         if ($headers) {
             $message[] = trim($headers, "\r\n") . "\r\n\r\n";
         }
         $message[] = $fp;
 
         return $this->append($mailbox, $message, $flags, $date, $binary);
     }
 
     /**
      * Returns QUOTA information
      *
      * @param string $mailbox Mailbox name
      *
      * @return array Quota information
      */
     public function getQuota($mailbox = null)
     {
         if ($mailbox === null || $mailbox === '') {
             $mailbox = 'INBOX';
         }
 
         // a0001 GETQUOTAROOT INBOX
         // * QUOTAROOT INBOX user/sample
         // * QUOTA user/sample (STORAGE 654 9765)
         // a0001 OK Completed
 
         list($code, $response) = $this->execute('GETQUOTAROOT', [$this->escape($mailbox)], 0, '/^\* QUOTA /i');
 
         $result   = false;
         $min_free = PHP_INT_MAX;
         $all      = [];
 
         if ($code == self::ERROR_OK) {
             foreach (explode("\n", $response) as $line) {
                 $tokens     = $this->tokenizeResponse($line, 3);
                 $quota_root = isset($tokens[2]) ? $tokens[2] : null;
                 $quotas     = $this->tokenizeResponse($line, 1);
 
                 if (empty($quotas)) {
                     continue;
                 }
 
                 foreach (array_chunk($quotas, 3) as $quota) {
                     list($type, $used, $total) = $quota;
                     $type = strtolower($type);
 
                     if ($type && $total) {
                         $all[$quota_root][$type]['used']  = intval($used);
                         $all[$quota_root][$type]['total'] = intval($total);
                     }
                 }
 
                 if (empty($all[$quota_root]['storage'])) {
                     continue;
                 }
 
                 $used  = $all[$quota_root]['storage']['used'];
                 $total = $all[$quota_root]['storage']['total'];
                 $free  = $total - $used;
 
                 // calculate lowest available space from all storage quotas
                 if ($free < $min_free) {
                     $min_free          = $free;
                     $result['used']    = $used;
                     $result['total']   = $total;
                     $result['percent'] = min(100, round(($used/max(1,$total))*100));
                     $result['free']    = 100 - $result['percent'];
                 }
             }
         }
 
         if (!empty($result)) {
             $result['all'] = $all;
         }
 
         return $result;
     }
 
     /**
      * Send the SETACL command (RFC4314)
      *
      * @param string $mailbox Mailbox name
      * @param string $user    User name
      * @param mixed  $acl     ACL string or array
      *
      * @return bool True on success, False on failure
      *
      * @since 0.5-beta
      */
     public function setACL($mailbox, $user, $acl)
     {
         if (is_array($acl)) {
             $acl = implode('', $acl);
         }
 
         $result = $this->execute('SETACL',
             [$this->escape($mailbox), $this->escape($user), strtolower($acl)],
             self::COMMAND_NORESPONSE
         );
 
         return $result == self::ERROR_OK;
     }
 
     /**
      * Send the DELETEACL command (RFC4314)
      *
      * @param string $mailbox Mailbox name
      * @param string $user    User name
      *
      * @return bool True on success, False on failure
      *
      * @since 0.5-beta
      */
     public function deleteACL($mailbox, $user)
     {
         $result = $this->execute('DELETEACL',
             [$this->escape($mailbox), $this->escape($user)],
             self::COMMAND_NORESPONSE
         );
 
         return $result == self::ERROR_OK;
     }
 
     /**
      * Send the GETACL command (RFC4314)
      *
      * @param string $mailbox Mailbox name
      *
      * @return array User-rights array on success, NULL on error
      * @since 0.5-beta
      */
     public function getACL($mailbox)
     {
         list($code, $response) = $this->execute('GETACL', [$this->escape($mailbox)], 0, '/^\* ACL /i');
 
         if ($code == self::ERROR_OK && $response) {
             // Parse server response (remove "* ACL ")
             $response = substr($response, 6);
             $ret  = $this->tokenizeResponse($response);
             $mbox = array_shift($ret);
             $size = count($ret);
 
             // Create user-rights hash array
             // @TODO: consider implementing fixACL() method according to RFC4314.2.1.1
             // so we could return only standard rights defined in RFC4314,
             // excluding 'c' and 'd' defined in RFC2086.
             if ($size % 2 == 0) {
                 for ($i=0; $i<$size; $i++) {
                     $ret[$ret[$i]] = str_split($ret[++$i]);
                     unset($ret[$i-1]);
                     unset($ret[$i]);
                 }
                 return $ret;
             }
 
             $this->setError(self::ERROR_COMMAND, "Incomplete ACL response");
         }
     }
 
     /**
      * Send the LISTRIGHTS command (RFC4314)
      *
      * @param string $mailbox Mailbox name
      * @param string $user    User name
      *
      * @return array List of user rights
      * @since 0.5-beta
      */
     public function listRights($mailbox, $user)
     {
         list($code, $response) = $this->execute('LISTRIGHTS',
             [$this->escape($mailbox), $this->escape($user)], 0, '/^\* LISTRIGHTS /i');
 
         if ($code == self::ERROR_OK && $response) {
             // Parse server response (remove "* LISTRIGHTS ")
             $response = substr($response, 13);
 
             $ret_mbox = $this->tokenizeResponse($response, 1);
             $ret_user = $this->tokenizeResponse($response, 1);
             $granted  = $this->tokenizeResponse($response, 1);
             $optional = trim($response);
 
             return [
                 'granted'  => str_split($granted),
                 'optional' => explode(' ', $optional),
             ];
         }
     }
 
     /**
      * Send the MYRIGHTS command (RFC4314)
      *
      * @param string $mailbox Mailbox name
      *
      * @return array MYRIGHTS response on success, NULL on error
      * @since 0.5-beta
      */
     public function myRights($mailbox)
     {
         list($code, $response) = $this->execute('MYRIGHTS', [$this->escape($mailbox)], 0, '/^\* MYRIGHTS /i');
 
         if ($code == self::ERROR_OK && $response) {
             // Parse server response (remove "* MYRIGHTS ")
             $response = substr($response, 11);
 
             $ret_mbox = $this->tokenizeResponse($response, 1);
             $rights   = $this->tokenizeResponse($response, 1);
 
             return str_split($rights);
         }
     }
 
     /**
      * Send the SETMETADATA command (RFC5464)
      *
      * @param string $mailbox Mailbox name
      * @param array  $entries Entry-value array (use NULL value as NIL)
      *
      * @return bool True on success, False on failure
      * @since 0.5-beta
      */
     public function setMetadata($mailbox, $entries)
     {
         if (!is_array($entries) || empty($entries)) {
             $this->setError(self::ERROR_COMMAND, "Wrong argument for SETMETADATA command");
             return false;
         }
 
         foreach ($entries as $name => $value) {
             $entries[$name] = $this->escape($name) . ' ' . $this->escape($value, true);
         }
 
         $entries = implode(' ', $entries);
         $result = $this->execute('SETMETADATA',
             [$this->escape($mailbox), '(' . $entries . ')'],
             self::COMMAND_NORESPONSE
         );
 
         return $result == self::ERROR_OK;
     }
 
     /**
      * Send the SETMETADATA command with NIL values (RFC5464)
      *
      * @param string $mailbox Mailbox name
      * @param array  $entries Entry names array
      *
      * @return bool True on success, False on failure
      *
      * @since 0.5-beta
      */
     public function deleteMetadata($mailbox, $entries)
     {
         if (!is_array($entries) && !empty($entries)) {
             $entries = explode(' ', $entries);
         }
 
         if (empty($entries)) {
             $this->setError(self::ERROR_COMMAND, "Wrong argument for SETMETADATA command");
             return false;
         }
 
         $data = [];
         foreach ($entries as $entry) {
             $data[$entry] = null;
         }
 
         return $this->setMetadata($mailbox, $data);
     }
 
     /**
      * Send the GETMETADATA command (RFC5464)
      *
      * @param string $mailbox Mailbox name
      * @param array  $entries Entries
      * @param array  $options Command options (with MAXSIZE and DEPTH keys)
      *
      * @return array GETMETADATA result on success, NULL on error
      *
      * @since 0.5-beta
      */
     public function getMetadata($mailbox, $entries, $options = [])
     {
         if (!is_array($entries)) {
             $entries = [$entries];
         }
 
         // create entries string
         foreach ($entries as $idx => $name) {
             $entries[$idx] = $this->escape($name);
         }
 
         $optlist = '';
         $entlist = '(' . implode(' ', $entries) . ')';
 
         // create options string
         if (is_array($options)) {
             $options = array_change_key_case($options, CASE_UPPER);
             $opts    = [];
 
             if (!empty($options['MAXSIZE'])) {
                 $opts[] = 'MAXSIZE '.intval($options['MAXSIZE']);
             }
             if (!empty($options['DEPTH'])) {
                 $opts[] = 'DEPTH '.intval($options['DEPTH']);
             }
 
             if ($opts) {
                 $optlist = '(' . implode(' ', $opts) . ')';
             }
         }
 
         $optlist .= ($optlist ? ' ' : '') . $entlist;
 
         list($code, $response) = $this->execute('GETMETADATA', [$this->escape($mailbox), $optlist]);
 
         if ($code == self::ERROR_OK) {
             $result = [];
             $data   = $this->tokenizeResponse($response);
 
             // The METADATA response can contain multiple entries in a single
             // response or multiple responses for each entry or group of entries
             for ($i = 0, $size = count($data); $i < $size; $i++) {
                 if ($data[$i] === '*'
                     && $data[++$i] === 'METADATA'
                     && is_string($mbox = $data[++$i])
                     && is_array($data[++$i])
                 ) {
                     for ($x = 0, $size2 = count($data[$i]); $x < $size2; $x += 2) {
                         if ($data[$i][$x+1] !== null) {
                             $result[$mbox][$data[$i][$x]] = $data[$i][$x+1];
                         }
                     }
                 }
             }
 
             return $result;
         }
     }
 
     /**
      * Send the SETANNOTATION command (draft-daboo-imap-annotatemore)
      *
      * @param string $mailbox Mailbox name
      * @param array  $data    Data array where each item is an array with
      *                        three elements: entry name, attribute name, value
      *
      * @return bool True on success, False on failure
      * @since 0.5-beta
      */
     public function setAnnotation($mailbox, $data)
     {
         if (!is_array($data) || empty($data)) {
             $this->setError(self::ERROR_COMMAND, "Wrong argument for SETANNOTATION command");
             return false;
         }
 
         foreach ($data as $entry) {
             // ANNOTATEMORE drafts before version 08 require quoted parameters
             $entries[] = sprintf('%s (%s %s)', $this->escape($entry[0], true),
                 $this->escape($entry[1], true), $this->escape($entry[2], true));
         }
 
         $entries = implode(' ', $entries);
         $result  = $this->execute('SETANNOTATION', [$this->escape($mailbox), $entries], self::COMMAND_NORESPONSE);
 
         return $result == self::ERROR_OK;
     }
 
     /**
      * Send the SETANNOTATION command with NIL values (draft-daboo-imap-annotatemore)
      *
      * @param string $mailbox Mailbox name
      * @param array  $data    Data array where each item is an array with
      *                        two elements: entry name and attribute name
      *
      * @return bool True on success, False on failure
      *
      * @since 0.5-beta
      */
     public function deleteAnnotation($mailbox, $data)
     {
         if (!is_array($data) || empty($data)) {
             $this->setError(self::ERROR_COMMAND, "Wrong argument for SETANNOTATION command");
             return false;
         }
 
         return $this->setAnnotation($mailbox, $data);
     }
 
     /**
      * Send the GETANNOTATION command (draft-daboo-imap-annotatemore)
      *
      * @param string $mailbox Mailbox name
      * @param array  $entries Entries names
      * @param array  $attribs Attribs names
      *
      * @return array Annotations result on success, NULL on error
      *
      * @since 0.5-beta
      */
     public function getAnnotation($mailbox, $entries, $attribs)
     {
         if (!is_array($entries)) {
             $entries = [$entries];
         }
 
         // create entries string
         // ANNOTATEMORE drafts before version 08 require quoted parameters
         foreach ($entries as $idx => $name) {
             $entries[$idx] = $this->escape($name, true);
         }
         $entries = '(' . implode(' ', $entries) . ')';
 
         if (!is_array($attribs)) {
             $attribs = [$attribs];
         }
 
         // create attributes string
         foreach ($attribs as $idx => $name) {
             $attribs[$idx] = $this->escape($name, true);
         }
         $attribs = '(' . implode(' ', $attribs) . ')';
 
         list($code, $response) = $this->execute('GETANNOTATION', [$this->escape($mailbox), $entries, $attribs]);
 
         if ($code == self::ERROR_OK) {
             $result     = [];
             $data       = $this->tokenizeResponse($response);
             $last_entry = null;
 
             // Here we returns only data compatible with METADATA result format
             if (!empty($data) && ($size = count($data))) {
                 for ($i=0; $i<$size; $i++) {
                     $entry = $data[$i];
                     if (isset($mbox) && is_array($entry)) {
                         $attribs = $entry;
                         $entry   = $last_entry;
                     }
                     else if ($entry == '*') {
                         if ($data[$i+1] == 'ANNOTATION') {
                             $mbox = $data[$i+2];
                             unset($data[$i]);   // "*"
                             unset($data[++$i]); // "ANNOTATION"
                             unset($data[++$i]); // Mailbox
                         }
                         // get rid of other untagged responses
                         else {
                             unset($mbox);
                             unset($data[$i]);
                         }
                         continue;
                     }
                     else if (isset($mbox)) {
                         $attribs = $data[++$i];
                     }
                     else {
                         unset($data[$i]);
                         continue;
                     }
 
                     if (!empty($attribs)) {
                         for ($x=0, $len=count($attribs); $x<$len;) {
                             $attr  = $attribs[$x++];
                             $value = $attribs[$x++];
                             if ($attr == 'value.priv' && $value !== null) {
                                 $result[$mbox]['/private' . $entry] = $value;
                             }
                             else if ($attr == 'value.shared' && $value !== null) {
                                 $result[$mbox]['/shared' . $entry] = $value;
                             }
                         }
                     }
 
                     $last_entry = $entry;
                     unset($data[$i]);
                 }
             }
 
             return $result;
         }
     }
 
     /**
      * Returns BODYSTRUCTURE for the specified message.
      *
      * @param string $mailbox Folder name
      * @param int    $id      Message sequence number or UID
      * @param bool   $is_uid  True if $id is an UID
      *
      * @return array|bool Body structure array or False on error.
      * @since 0.6
      */
     public function getStructure($mailbox, $id, $is_uid = false)
     {
         $result = $this->fetch($mailbox, $id, $is_uid, ['BODYSTRUCTURE']);
 
         if (is_array($result) && !empty($result)) {
             $result = array_first($result);
             return $result->bodystructure;
         }
 
         return false;
     }
 
     /**
      * Returns data of a message part according to specified structure.
      *
      * @param array  $structure Message structure (getStructure() result)
      * @param string $part      Message part identifier
      *
      * @return array Part data as hash array (type, encoding, charset, size)
      */
     public static function getStructurePartData($structure, $part)
     {
         $part_a = self::getStructurePartArray($structure, $part);
         $data   = [];
 
         if (empty($part_a)) {
             return $data;
         }
 
         // content-type
         if (is_array($part_a[0])) {
             $data['type'] = 'multipart';
         }
         else {
             $data['type']     = strtolower($part_a[0]);
             $data['subtype']  = strtolower($part_a[1]);
             $data['encoding'] = strtolower($part_a[5]);
 
             // charset
             if (is_array($part_a[2])) {
                foreach ($part_a[2] as $key => $val) {
                     if (strcasecmp($val, 'charset') == 0) {
                         $data['charset'] = $part_a[2][$key+1];
                         break;
                     }
                 }
             }
         }
 
         // size
         $data['size'] = intval($part_a[6]);
 
         return $data;
     }
 
     public static function getStructurePartArray($a, $part)
     {
         if (!is_array($a)) {
             return false;
         }
 
         if (empty($part)) {
             return $a;
         }
 
         $ctype = is_string($a[0]) && is_string($a[1]) ? $a[0] . '/' . $a[1] : '';
 
         if (strcasecmp($ctype, 'message/rfc822') == 0) {
             $a = $a[8];
         }
 
         if (strpos($part, '.') > 0) {
             $orig_part = $part;
             $pos       = strpos($part, '.');
             $rest      = substr($orig_part, $pos+1);
             $part      = substr($orig_part, 0, $pos);
 
             return self::getStructurePartArray($a[$part-1], $rest);
         }
         else if ($part > 0) {
             return is_array($a[$part-1]) ? $a[$part-1] : $a;
         }
     }
 
     /**
      * Creates next command identifier (tag)
      *
      * @return string Command identifier
      * @since 0.5-beta
      */
     public function nextTag()
     {
         $this->cmd_num++;
         $this->cmd_tag = sprintf('A%04d', $this->cmd_num);
 
         return $this->cmd_tag;
     }
 
     /**
      * Sends IMAP command and parses result
      *
      * @param string $command   IMAP command
      * @param array  $arguments Command arguments
      * @param int    $options   Execution options
      * @param string $filter    Line filter (regexp)
      *
      * @return mixed Response code or list of response code and data
      * @since 0.5-beta
      */
     public function execute($command, $arguments = [], $options = 0, $filter = null)
     {
         $tag      = $this->nextTag();
         $query    = $tag . ' ' . $command;
         $noresp   = ($options & self::COMMAND_NORESPONSE);
         $response = $noresp ? null : '';
 
         if (!empty($arguments)) {
             foreach ($arguments as $arg) {
                 $query .= ' ' . self::r_implode($arg);
             }
         }
 
         // Send command
         if (!$this->putLineC($query, true, ($options & self::COMMAND_ANONYMIZED))) {
             preg_match('/^[A-Z0-9]+ ((UID )?[A-Z]+)/', $query, $matches);
             $cmd = $matches[1] ?: 'UNKNOWN';
             $this->setError(self::ERROR_COMMAND, "Failed to send $cmd command");
 
             return $noresp ? self::ERROR_COMMAND : [self::ERROR_COMMAND, ''];
         }
 
         // Parse response
         do {
             $line = $this->readFullLine(4096);
 
             if ($response !== null) {
                 if (!$filter || preg_match($filter, $line)) {
                     $response .= $line;
                 }
             }
 
             // parse untagged response for [COPYUID 1204196876 3456:3457 123:124] (RFC6851)
             if ($line && $command == 'UID MOVE') {
                 if (preg_match("/^\* OK \[COPYUID [0-9]+ ([0-9,:]+) ([0-9,:]+)\]/i", $line, $m)) {
                     $this->data['COPYUID'] = [$m[1], $m[2]];
                 }
             }
         }
         while (!$this->startsWith($line, $tag . ' ', true, true));
 
         $code = $this->parseResult($line, $command . ': ');
 
         // Remove last line from response
         if ($response) {
             if (!$filter) {
                 $line_len = min(strlen($response), strlen($line));
                 $response = substr($response, 0, -$line_len);
             }
 
             $response = rtrim($response, "\r\n");
         }
 
         // optional CAPABILITY response
         if (($options & self::COMMAND_CAPABILITY) && $code == self::ERROR_OK
             && preg_match('/\[CAPABILITY ([^]]+)\]/i', $line, $matches)
         ) {
             $this->parseCapability($matches[1], true);
         }
 
         // return last line only (without command tag, result and response code)
         if ($line && ($options & self::COMMAND_LASTLINE)) {
             $response = preg_replace("/^$tag (OK|NO|BAD|BYE|PREAUTH)?\s*(\[[a-z-]+\])?\s*/i", '', trim($line));
         }
 
         return $noresp ? $code : [$code, $response];
     }
 
     /**
      * Splits IMAP response into string tokens
      *
      * @param string &$str The IMAP's server response
      * @param int    $num  Number of tokens to return
      *
      * @return mixed Tokens array or string if $num=1
      * @since 0.5-beta
      */
     public static function tokenizeResponse(&$str, $num=0)
     {
         $result = [];
 
         while (!$num || count($result) < $num) {
             // remove spaces from the beginning of the string
             $str = ltrim($str);
 
             // empty string
             if ($str === '' || $str === null) {
                 break;
             }
 
             switch ($str[0]) {
 
             // String literal
             case '{':
                 if (($epos = strpos($str, "}\r\n", 1)) == false) {
                     // error
                 }
                 if (!is_numeric(($bytes = substr($str, 1, $epos - 1)))) {
                     // error
                 }
 
                 $result[] = $bytes ? substr($str, $epos + 3, $bytes) : '';
                 $str      = substr($str, $epos + 3 + $bytes);
                 break;
 
             // Quoted string
             case '"':
                 $len = strlen($str);
 
                 for ($pos=1; $pos<$len; $pos++) {
                     if ($str[$pos] == '"') {
                         break;
                     }
                     if ($str[$pos] == "\\") {
                         if ($str[$pos + 1] == '"' || $str[$pos + 1] == "\\") {
                             $pos++;
                         }
                     }
                 }
 
                 // we need to strip slashes for a quoted string
                 $result[] = stripslashes(substr($str, 1, $pos - 1));
                 $str      = substr($str, $pos + 1);
                 break;
 
             // Parenthesized list
             case '(':
                 $str      = substr($str, 1);
                 $result[] = self::tokenizeResponse($str);
                 break;
 
             case ')':
                 $str = substr($str, 1);
                 return $result;
 
             // String atom, number, astring, NIL, *, %
             default:
                 // excluded chars: SP, CTL, ), DEL
                 // we do not exclude [ and ] (#1489223)
                 if (preg_match('/^([^\x00-\x20\x29\x7F]+)/', $str, $m)) {
                     $result[] = $m[1] == 'NIL' ? null : $m[1];
                     $str      = substr($str, strlen($m[1]));
                 }
 
                 break;
             }
         }
 
         return $num == 1 ? (isset($result[0]) ? $result[0] : '') : $result;
     }
 
     /**
      * Joins IMAP command line elements (recursively)
      */
     protected static function r_implode($element)
     {
         if (!is_array($element)) {
             return $element;
         }
 
         reset($element);
 
         $string = '';
 
         foreach ($element as $value) {
             $string .= ' ' . self::r_implode($value);
         }
 
         return '(' . trim($string) . ')';
     }
 
     /**
      * Converts message identifiers array into sequence-set syntax
      *
      * @param array $messages Message identifiers
      * @param bool  $force    Forces compression of any size
      *
      * @return string Compressed sequence-set
      */
     public static function compressMessageSet($messages, $force = false)
     {
         // given a comma delimited list of independent mid's,
         // compresses by grouping sequences together
         if (!is_array($messages)) {
             // if less than 255 bytes long, let's not bother
             if (!$force && strlen($messages) < 255) {
                 return preg_match('/[^0-9:,*]/', $messages) ? 'INVALID' : $messages;
             }
 
             // see if it's already been compressed
             if (strpos($messages, ':') !== false) {
                 return preg_match('/[^0-9:,*]/', $messages) ? 'INVALID' : $messages;
             }
 
             // separate, then sort
             $messages = explode(',', $messages);
         }
 
         sort($messages);
 
         $result = [];
         $start  = $prev = $messages[0];
 
         foreach ($messages as $id) {
             $incr = $id - $prev;
             if ($incr > 1) { // found a gap
                 if ($start == $prev) {
                     $result[] = $prev; // push single id
                 }
                 else {
                     $result[] = $start . ':' . $prev; // push sequence as start_id:end_id
                 }
                 $start = $id; // start of new sequence
             }
             $prev = $id;
         }
 
         // handle the last sequence/id
         if ($start == $prev) {
             $result[] = $prev;
         }
         else {
             $result[] = $start.':'.$prev;
         }
 
         // return as comma separated string
         $result = implode(',', $result);
 
         return preg_match('/[^0-9:,*]/', $result) ? 'INVALID' : $result;
     }
 
     /**
      * Converts message sequence-set into array
      *
      * @param string $messages Message identifiers
      *
      * @return array List of message identifiers
      */
     public static function uncompressMessageSet($messages)
     {
         if (empty($messages)) {
             return [];
         }
 
         $result   = [];
         $messages = explode(',', $messages);
 
         foreach ($messages as $idx => $part) {
             $items = explode(':', $part);
 
             if (!empty($items[1]) && $items[1] > $items[0]) {
                 $max = $items[1];
             }
             else {
                 $max = $items[0];
             }
 
             for ($x = $items[0]; $x <= $max; $x++) {
                 $result[] = (int) $x;
             }
 
             unset($messages[$idx]);
         }
 
         return $result;
     }
 
     /**
      * Clear internal status cache
      */
     protected function clear_status_cache($mailbox)
     {
         unset($this->data['STATUS:' . $mailbox]);
 
         $keys = ['EXISTS', 'RECENT', 'UNSEEN', 'UID-MAP'];
 
         foreach ($keys as $key) {
             unset($this->data[$key]);
         }
     }
 
     /**
      * Clear internal cache of the current mailbox
      */
     protected function clear_mailbox_cache()
     {
         $this->clear_status_cache($this->selected);
 
         $keys = ['UIDNEXT', 'UIDVALIDITY', 'HIGHESTMODSEQ', 'NOMODSEQ',
             'PERMANENTFLAGS', 'QRESYNC', 'VANISHED', 'READ-WRITE'];
 
         foreach ($keys as $key) {
             unset($this->data[$key]);
         }
     }
 
     /**
      * Converts flags array into string for inclusion in IMAP command
      *
      * @param array $flags Flags (see self::flags)
      *
      * @return string Space-separated list of flags
      */
     protected function flagsToStr($flags)
     {
         foreach ((array) $flags as $idx => $flag) {
             if ($flag = $this->flags[strtoupper($flag)]) {
                 $flags[$idx] = $flag;
             }
         }
 
         return implode(' ', (array) $flags);
     }
 
     /**
      * CAPABILITY response parser
      */
     protected function parseCapability($str, $trusted=false)
     {
         $str = preg_replace('/^\* CAPABILITY /i', '', $str);
 
         $this->capability = explode(' ', strtoupper($str));
 
         if (!empty($this->prefs['disabled_caps'])) {
             $this->capability = array_diff($this->capability, $this->prefs['disabled_caps']);
         }
 
         if (!isset($this->prefs['literal+']) && in_array('LITERAL+', $this->capability)) {
             $this->prefs['literal+'] = true;
         }
         else if (!isset($this->prefs['literal-']) && in_array('LITERAL-', $this->capability)) {
             $this->prefs['literal-'] = true;
         }
 
         if ($trusted) {
             $this->capability_read = true;
         }
     }
 
     /**
      * Escapes a string when it contains special characters (RFC3501)
      *
      * @param string $string       IMAP string
      * @param bool   $force_quotes Forces string quoting (for atoms)
      *
      * @return string String atom, quoted-string or string literal
      * @todo lists
      */
     public static function escape($string, $force_quotes = false)
     {
         if ($string === null) {
             return 'NIL';
         }
 
         if ($string === '') {
             return '""';
         }
 
         // atom-string (only safe characters)
         if (!$force_quotes && !preg_match('/[\x00-\x20\x22\x25\x28-\x2A\x5B-\x5D\x7B\x7D\x80-\xFF]/', $string)) {
             return $string;
         }
 
         // quoted-string
         if (!preg_match('/[\r\n\x00\x80-\xFF]/', $string)) {
             return '"' . addcslashes($string, '\\"') . '"';
         }
 
         // literal-string
         return sprintf("{%d}\r\n%s", strlen($string), $string);
     }
 
     /**
      * Set the value of the debugging flag.
      *
      * @param bool     $debug   New value for the debugging flag.
      * @param callback $handler Logging handler function
      *
      * @since 0.5-stable
      */
     public function setDebug($debug, $handler = null)
     {
         $this->debug         = $debug;
         $this->debug_handler = $handler;
     }
 
     /**
      * Write the given debug text to the current debug output handler.
      *
      * @param string $message Debug message text.
      *
      * @since 0.5-stable
      */
     protected function debug($message)
     {
         if (($len = strlen($message)) > self::DEBUG_LINE_LENGTH) {
             $diff    = $len - self::DEBUG_LINE_LENGTH;
             $message = substr($message, 0, self::DEBUG_LINE_LENGTH)
                 . "... [truncated $diff bytes]";
         }
 
         if ($this->resourceid) {
             $message = sprintf('[%s] %s', $this->resourceid, $message);
         }
 
         if ($this->debug_handler) {
             call_user_func_array($this->debug_handler, [$this, $message]);
         }
         else {
             echo "DEBUG: $message\n";
         }
     }
 }