Exchange generates failure report emails for Inbox items which haven't attempted to be synced

Question

Hello,Our ActiveSync client is reporting errors to the user when the user is sent certain types of recurrence invites. If an invite to a meeting is sent from the Outlook Web App to the user, and the user then syncs their Inbox (using our ActiveSync client and the Sync command), instead of receiving the correct email, they will get an email indicating an error:
From: Microsoft Exchange on Behalf of *user’s name*
Subject: Synchronization with your WinRT failed for 1 items.
Body:
Synchronization with your Winrt failed for 1 items.
The following items couldn’t be sent to your mobile phone. They haven’t been deleted …
Item Folder: Inbox
Item Type: IPM.Schedule.Meeting.Request
Item Created: *date*
Item Subject: *subject of missing email*
(WinRT is the name of our client currently.)
This occurs consistently when the invite is for a recurring meeting, which occurs on the last day of a month, yearly. (Yearly on the nth day of the month)
It also seems that after one of these error emails appears, other items start to be added in with it, although this could just be the result on my side from a lot of testing side effects.
There’s two strange things to note about this error.
The Exchange server never attempts to even send the items via ActiveSync to our client, so the error does not seem to be caused by our Sync request. I’ve used Fiddler to examine the calls, and we never receive the original message in any form.
The Windows Mail client (in Windows 8.1), which uses ActiveSync, has no problem Syncing the very same items that are causing the errors to appear. This gives the impression that something can be done to remedy the problem, but I have no idea what.Thanks
ArchieCoder

Answer 1

Hello ArchieCoder,
This is certainly not what I would expect to see. However, I can't say with certainty that it's related to the syncing issue.
I went back and looked at the Fiddler trace you took from the Windows Mail client. It gets the same FolderSync response. The first three folders in the response look like I expect--Calendar has ServerId 1, Contacts has ServerId 2, and Deleted Items has ServerId
3. After that, the ServerId value jumps to 11 for the Drafts folder, so it and all of the subsequent folders have a ServerId value that is 7 higher than what I would expect to see.
What seems especially weird to me is that the Windows Mail client proceeds to issue a Sync request for the list of CollectionIds I reported earlier, despite several of them being absent from the FolderSync response. Furthermore, it looks like the Windows
Mail client is getting Inbox items that are identified as being in CollectionId 5:
<?xml version="1.0" encoding="utf-8"?>
<airsync:Sync xmlns:airsync="AirSync">
   <airsync:Collections>
      <airsync:Collection>
         <airsync:SyncKey>933450273</airsync:SyncKey>
         <airsync:CollectionId>5</airsync:CollectionId>
         <airsync:Status>1</airsync:Status>
         <airsync:Commands>
            <airsync:Add>
               <airsync:ServerId>5:391</airsync:ServerId>
               <airsync:ApplicationData>
                  <email:Subject>Canceled: Last day of december</email:Subject>
I'm really at a loss for what is going on with this. How difficult would it be for you to test this with your client assuming that Inbox is CollectionId 5 instead of the 12 that is returned from the FolderSync? I am afraid we might be focusing too closely
on this particular aspect of the issue without being sure it could be causing the real problem, so I think it would be good if you can either reproduce the failure syncing CollectionId 5 instead of 12, or show that your client fails in some other way if it
tries to sync CollectionId 5. A Fiddler trace of the outcome of that test including both the FolderSync response and Sync request/response would be the next logical step here, I think, assuming that that is doable. Please let me know what you think.
Best regards,
Matt Weber | Microsoft Open Specifications Team