diff --git a/ActiveSync/SOGoActiveSyncDispatcher+Sync.m b/ActiveSync/SOGoActiveSyncDispatcher+Sync.m
index dfa0b3110..551551e8d 100644
--- a/ActiveSync/SOGoActiveSyncDispatcher+Sync.m
+++ b/ActiveSync/SOGoActiveSyncDispatcher+Sync.m
@@ -571,24 +571,27 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     case ActiveSyncMailFolder:
     default:
       {
+        NSMutableArray *addedOrChangedMessages;
         SOGoMailObject *mailObject;
         NSString *uid, *command;
         NSDictionary *aMessage;
         NSArray *allMessages;
-        
+        int deleted_count;
+
         allMessages = [theCollection syncTokenFieldsWithProperties: nil   matchingSyncToken: theSyncKey  fromDate: theFilterType];
-        
+        addedOrChangedMessages = [NSMutableArray array];
+        deleted_count = 0;
+
         // Check for the WindowSize.
         // FIXME: we should eventually check for modseq and slice the maximum
         //        amount of messages returned to ensure we don't have the same
         //        modseq accross contiguous boundaries
         max = [allMessages count];
-        if (max > theWindowSize)
-          {
-            max = theWindowSize;
-            more_available = YES;
-          }
         
+        // We first check the number of deleted messages we have
+        // We do NOT honor the window size here as it seems to be
+        // impossible to get the modseq of an expunged message so
+        // we can't iterate in the list of deleted messages.
         for (i = 0; i < max; i++)
           {
             aMessage = [allMessages objectAtIndex: i];
@@ -601,31 +604,53 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
                 [s appendString: @"<Delete xmlns=\"AirSync:\">"];
                 [s appendFormat: @"<ServerId xmlns=\"AirSync:\">%@</ServerId>", uid];
                 [s appendString: @"</Delete>"];
+                deleted_count++;
               }
             else
               {
-                if ([command isEqualToString: @"added"])
-                  [s appendString: @"<Add xmlns=\"AirSync:\">"];
-                else
-                  [s appendString: @"<Change xmlns=\"AirSync:\">"];
-
-                mailObject = [theCollection lookupName: uid
-                                             inContext: context
-                                               acquire: 0];
-
-                [s appendFormat: @"<ServerId xmlns=\"AirSync:\">%@</ServerId>", uid];
-                [s appendString: @"<ApplicationData xmlns=\"AirSync:\">"];
-                [s appendString: [mailObject activeSyncRepresentationInContext: context]];
-                [s appendString: @"</ApplicationData>"];
-                
-                if ([command isEqualToString: @"added"])
-                  [s appendString: @"</Add>"];
-                else
-                  [s appendString: @"</Change>"];
-
+                [addedOrChangedMessages addObject: aMessage];
               }
           }
 
+        // We then "pad" with our added/changed messages. We ALWAYS
+        // at least return one if available
+        max = [addedOrChangedMessages count];
+        
+        for (i = 0; i < max; i++)
+          {
+            aMessage = [addedOrChangedMessages objectAtIndex: i];
+            
+            uid = [[[aMessage allKeys] lastObject] stringValue];
+            command = [[aMessage allValues] lastObject];          
+            
+            if ([command isEqualToString: @"added"])
+              [s appendString: @"<Add xmlns=\"AirSync:\">"];
+            else
+              [s appendString: @"<Change xmlns=\"AirSync:\">"];
+            
+            mailObject = [theCollection lookupName: uid
+                                             inContext: context
+                                           acquire: 0];
+            
+            [s appendFormat: @"<ServerId xmlns=\"AirSync:\">%@</ServerId>", uid];
+            [s appendString: @"<ApplicationData xmlns=\"AirSync:\">"];
+            [s appendString: [mailObject activeSyncRepresentationInContext: context]];
+            [s appendString: @"</ApplicationData>"];
+            
+            if ([command isEqualToString: @"added"])
+              [s appendString: @"</Add>"];
+            else
+              [s appendString: @"</Change>"];
+            
+            
+            // We check if we must stop padding
+            if (i+1+deleted_count > theWindowSize)
+              {
+                more_available = YES;
+                break;
+              }
+          }
+      
         //
         if (more_available)
           {
diff --git a/NEWS b/NEWS
index 09a3bb241..4a3a731b5 100644
--- a/NEWS
+++ b/NEWS
@@ -14,6 +14,7 @@ Bug fixes
  - fixed encoding of mail folder name when creating a subfolder (#2637)
  - fixed returned date format for email messages in Active Sync
  - fixed missing 'name part' in address for email messages in Active Sync
+ - fixed race condition when syncing huge amount of deleted messages over Active Sync
 
 2.2.0 (2014-02-24)
 ------------------
diff --git a/SoObjects/Mailer/SOGoMailFolder.m b/SoObjects/Mailer/SOGoMailFolder.m
index abf4bf100..7f45ec814 100644
--- a/SoObjects/Mailer/SOGoMailFolder.m
+++ b/SoObjects/Mailer/SOGoMailFolder.m
@@ -1940,8 +1940,11 @@ static NSString *defaultUserID =  @"anyone";
       uid = [theId intValue];
       result = [[imap4 client] fetchModseqForUid: uid];
       modseq = [[[[result objectForKey: @"RawResponse"]  objectForKey: @"fetch"] objectForKey: @"modseq"] intValue];
-        
-      tag = [NSString stringWithFormat: @"%d-%d", uid, modseq-1];
+      
+      if (modseq < 1)
+        modseq = 1;
+
+      tag = [NSString stringWithFormat: @"%d-%d", uid, modseq];
     }
 
   return tag;
@@ -1999,7 +2002,7 @@ static NSString *defaultUserID =  @"anyone";
 // Check updated items
 //
 //
-// . uid fetch 1:* (FLAGS) (changedsince 171)
+// . uid fetch 1:* (UID) (changedsince 171)
 //
 // To get the modseq of a specific message:
 //
@@ -2101,11 +2104,14 @@ static NSString *defaultUserID =  @"anyone";
   // We fetch deleted ones
   if (highestmodseq > 0)
     {
+      id uid;
+
       uids = [self fetchUIDsOfVanishedItems: highestmodseq];
       
       for (i = 0; i < [uids count]; i++)
         {
-          d = [NSDictionary dictionaryWithObject: @"deleted"  forKey: [uids objectAtIndex: i]];
+          uid = [uids objectAtIndex: i];
+          d = [NSDictionary dictionaryWithObject: @"deleted"  forKey: uid];
           [allTokens addObject: d];
         }
     }