diff --git a/lib/ext/Syncroton/Command/ItemOperations.php b/lib/ext/Syncroton/Command/ItemOperations.php
--- a/lib/ext/Syncroton/Command/ItemOperations.php
+++ b/lib/ext/Syncroton/Command/ItemOperations.php
@@ -251,7 +251,11 @@
                     }
                 }
             }
-            
+
+            if(isset($fetch->Options->MIMESupport)){
+                $fetchArray['options']['mimeSupport']=(int)$fetch->Options->MIMESupport;
+            }
+ 
             if (isset($airSyncBase->Range)) {
                 $fetchArray['options']['range'] = (string) $airSyncBase->Range;
             }
diff --git a/lib/kolab_sync_data_email.php b/lib/kolab_sync_data_email.php
--- a/lib/kolab_sync_data_email.php
+++ b/lib/kolab_sync_data_email.php
@@ -319,8 +319,15 @@
         $result['nativeBodyType'] = $message->has_html_part() ? 2 : 1;
 
         // Message class
-        // @TODO: add messageClass suffix for encrypted messages
-        $result['messageClass'] = 'IPM.Note';
+        if($headers->ctype == 'multipart/signed' && $struct->parts[1] && $struct->parts[1]->mimetype == 'application/pkcs7-signature' ){
+            $result['messageClass'] = 'IPM.Note.SMIME.MultipartSigned';
+        }
+        elseif($headers->ctype == 'application/pkcs7-mime' || $headers->ctype == 'application/x-pkcs7-mime'){
+            $result['messageClass'] = 'IPM.Note.SMIME';
+        }
+        else{
+            $result['messageClass'] = 'IPM.Note';
+        }
         $result['contentClass'] = 'urn:content-classes:message';
 
         // Categories (Tags)