[Tickets #12945] Re: ActiveSync: Deleting one email in Outlook 2013 results in two mails in Outlook 2013 trash folder

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Ticket URL: http://bugs.horde.org/ticket/12945
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  Ticket             | 12945
  Updated By         | chrissi at amusing.de
  Summary            | ActiveSync: Deleting one email in Outlook 2013 results
                     | in two mails in Outlook 2013 trash folder
  Queue              | Synchronization
  Version            | Git master
  Type               | Bug
  State              | Not A Bug
  Priority           | 1. Low
  Milestone          |
  Patch              |
  Owners             | Michael Rubinsky
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chrissi at amusing.de (2014-01-30 15:52) wrote:

>> Hello,
>>
>> I experienced a litte bug when using Outlook 2013 via ActiveSync to
>> connect to Horde.
>> When I delete an email in Outlook 2013, it is moved to the trash
>> folder correctly. After a few seconds exactly the same email appears
>> in the trash folder, so you now see the deleted email twice.
>> This second email appears only in Outlook, you don't see it in the
>> Horde webmail trash.
>
> This is a known issue. OL is sending a MOVE command to move the  
> email to the trash folder (which is correct), but it ALSO manually  
> moves the email locally (this is incorrect). All the client is  
> supposed to do is remove the email from the old mailbox. The server,  
> in response to the MOVE command moves the email to the new folder  
> (In this case the Trash folder) and the change is then picked up on  
> the next SYNC or PING cycle. SInce OL is manually moving the email,  
> the server has no idea it is already in the mailbox (the protocol  
> provides no mechanism for this, all changes are done server side and  
> sent to the client).
>
>> If you compare the header of the two emails, it slightly differs in
>> the "Content-Type" field, everything else is exactly the same.
>>
>> Deleted email:
>> Content-Type: multipart/alternative; boundary="=_7CrMzMy6GwiFZgAVh3gsUw9"
>>
>> Email which appeared some seconds later:
>> Content-Type: multipart/alternative; boundary="=_yt_nh4i36nWWv2czhvKVfQ1"
>>
>> It seems as when the deleted email is synced to Horde it's header
>> gets changed, so Outlook 2013 sees it as a new item and downloads it
>> again.
>
> No. This is not how sync works. The client doesn't "download" an  
> email based on any criteria. The server knows what messages were  
> sent to the client based on the message's UID, not any other header  
> values and detects any changes in the mailboxes on the IMAP server.  
> These changes are sent to the client. Any client initiated changes  
> are sent as commands to the server, i.e., "move this message from  
> the INBOX to the Trash folder please". The server performs the  
> command and tells the client the results, i.e., "I moved the email  
> from the INBOX to the Trash folder and it has the following UID  
> value: 432. You should remove the old copy of the email from the  
> INBOX folder."
>
>> If you need any further information please don't hesitate to contact me!
>>
>> Best regards,
>> Christian Hailer

OK, thank you very much for the explanation!
In the meantime I tried to reproduce the same scenario with my Hotmail  
account, it can be used via ActiveSync as well.
With Hotmail it doesn't happen, meaning when I delete an email there  
isn't a second one in the trash folder afterwards ... what could be  
different there?

Best regards,
Christian