diff --git a/resources/imap/setupserver.h b/resources/imap/setupserver.h
--- a/resources/imap/setupserver.h
+++ b/resources/imap/setupserver.h
@@ -93,6 +93,7 @@
   KPIMIdentities::IdentityCombo *m_identityCombobox;
   QString m_oldResourceName;
   QRegExpValidator mValidator;
+  QRegExpValidator mSieveUrlValidator;
   Akonadi::Collection mOldTrash;
   FolderArchiveSettingPage *m_folderArchiveSettingPage;
 
diff --git a/resources/imap/setupserver.cpp b/resources/imap/setupserver.cpp
--- a/resources/imap/setupserver.cpp
+++ b/resources/imap/setupserver.cpp
@@ -149,6 +149,10 @@
   mValidator.setRegExp( QRegExp( QLatin1String("[A-Za-z0-9-_:.]*") ) );
   m_ui->imapServer->setValidator( &mValidator );
 
+  // regex for evaluating a valid sieve url
+  mSieveUrlValidator.setRegExp(QRegExp(QLatin1String("(sieve://)?[A-Za-z0-9-_.]*(:[0-9]+)?(/.*)?")));
+  m_ui->alternateURL->setValidator(&mSieveUrlValidator);
+
   m_ui->folderRequester->setMimeTypeFilter(
     QStringList() << KMime::Message::mimeType() );
   m_ui->folderRequester->setAccessRightsFilter( Akonadi::Collection::CanChangeItem | Akonadi::Collection::CanCreateItem | Akonadi::Collection::CanDeleteItem );
@@ -187,6 +191,7 @@
   slotTestChanged();
   slotComplete();
   slotCustomSieveChanged();
+  slotEnableWidgets();
 #ifndef IMAPRESOURCE_NO_SOLID
   connect( Solid::Networking::notifier(),
            SIGNAL(statusChanged(Solid::Networking::Status)),
@@ -290,7 +295,19 @@
   m_parentResource->settings()->setSieveSupport( m_ui->managesieveCheck->isChecked() );
   m_parentResource->settings()->setSieveReuseConfig( m_ui->sameConfigCheck->isChecked() );
   m_parentResource->settings()->setSievePort( m_ui->sievePortSpin->value() );
-  m_parentResource->settings()->setSieveAlternateUrl( m_ui->alternateURL->text() );
+  if (!m_ui->alternateURL->text().isEmpty()) {
+    QRegExp sieveurl(QLatin1String("(sieve://)?([A-Za-z0-9-_.]+)(:[0-9]+)?((/|\\?).*)?"));
+    sieveurl.exactMatch(m_ui->alternateURL->text());
+    QString server = sieveurl.cap(2);
+    QString port = sieveurl.cap(3);
+    QString localPart = sieveurl.cap(4);
+    if (port.isEmpty()) {
+        port = QLatin1String(":4190");
+    }
+    m_parentResource->settings()->setSieveAlternateUrl(QLatin1String("sieve://")+server+port+localPart);
+  } else {
+    m_parentResource->settings()->setSieveAlternateUrl(QString());
+  }
   m_parentResource->settings()->setSieveVacationFilename( m_vacationFileName );
 
   m_parentResource->settings()->setTrashCollection( m_ui->folderRequester->collection().id() );
diff --git a/resources/imap/setupserverview_desktop.ui b/resources/imap/setupserverview_desktop.ui
--- a/resources/imap/setupserverview_desktop.ui
+++ b/resources/imap/setupserverview_desktop.ui
@@ -231,6 +231,9 @@
          </item>
          <item>
           <widget class="KLineEdit" name="alternateURL">
+              <property name="placeholderText">
+               <string>sieve://server:port</string>
+              </property>
               <property name="trapReturnKey">
                <bool>true</bool>
               </property>
diff --git a/resources/kolab/setupserver.h b/resources/kolab/setupserver.h
--- a/resources/kolab/setupserver.h
+++ b/resources/kolab/setupserver.h
@@ -93,6 +93,7 @@
   KPIMIdentities::IdentityCombo *m_identityCombobox;
   QString m_oldResourceName;
   QRegExpValidator mValidator;
+  QRegExpValidator mSieveUrlValidator;
   Akonadi::Collection mOldTrash;
   FolderArchiveSettingPage *m_folderArchiveSettingPage;
 
diff --git a/resources/kolab/setupserver.cpp b/resources/kolab/setupserver.cpp
--- a/resources/kolab/setupserver.cpp
+++ b/resources/kolab/setupserver.cpp
@@ -153,6 +153,10 @@
   mValidator.setRegExp( QRegExp( QLatin1String("[A-Za-z0-9-_:.]*") ) );
   m_ui->imapServer->setValidator( &mValidator );
 
+  // regex for evaluating a valid sieve url
+  mSieveUrlValidator.setRegExp(QRegExp(QLatin1String("(sieve://)?[A-Za-z0-9-_.]*(:[0-9]+)?((/|\\?).*)?")));
+  m_ui->alternateURL->setValidator(&mSieveUrlValidator);
+
   m_ui->folderRequester->setMimeTypeFilter(
     QStringList() << KMime::Message::mimeType() );
   m_ui->folderRequester->setAccessRightsFilter( Akonadi::Collection::CanChangeItem | Akonadi::Collection::CanCreateItem | Akonadi::Collection::CanDeleteItem );
@@ -191,6 +195,7 @@
   slotTestChanged();
   slotComplete();
   slotCustomSieveChanged();
+  slotEnableWidgets();
 #ifndef IMAPRESOURCE_NO_SOLID
   connect( Solid::Networking::notifier(),
            SIGNAL(statusChanged(Solid::Networking::Status)),
@@ -294,7 +299,19 @@
   m_parentResource->settings()->setSieveSupport( m_ui->managesieveCheck->isChecked() );
   m_parentResource->settings()->setSieveReuseConfig( m_ui->sameConfigCheck->isChecked() );
   m_parentResource->settings()->setSievePort( m_ui->sievePortSpin->value() );
-  m_parentResource->settings()->setSieveAlternateUrl( m_ui->alternateURL->text() );
+  if (!m_ui->alternateURL->text().isEmpty()) {
+    QRegExp sieveurl(QLatin1String("(sieve://)?([A-Za-z0-9-_.]+)(:[0-9]+)?((/|\\?).*)?"));
+    sieveurl.exactMatch(m_ui->alternateURL->text());
+    QString server = sieveurl.cap(2);
+    QString port = sieveurl.cap(3);
+    QString localPart = sieveurl.cap(4);
+    if (port.isEmpty()) {
+        port = QLatin1String(":4190");
+    }
+    m_parentResource->settings()->setSieveAlternateUrl(QLatin1String("sieve://")+server+port+localPart);
+  } else {
+    m_parentResource->settings()->setSieveAlternateUrl(QString());
+  }
   m_parentResource->settings()->setSieveVacationFilename( m_vacationFileName );
 
   m_parentResource->settings()->setTrashCollection( m_ui->folderRequester->collection().id() );
diff --git a/resources/kolab/setupserverview_desktop.ui b/resources/kolab/setupserverview_desktop.ui
--- a/resources/kolab/setupserverview_desktop.ui
+++ b/resources/kolab/setupserverview_desktop.ui
@@ -245,6 +245,9 @@
          </item>
          <item>
           <widget class="KLineEdit" name="alternateURL">
+           <property name="placeholderText">
+            <string>sieve://server:port</string>
+           </property>
            <property name="trapReturnKey" stdset="0">
             <bool>true</bool>
            </property>