Sync dovecot to cyrus imap, creates many X-OfflineIMAP headers

Sebastian Spaeth Sebastian at
Thu Aug 18 08:22:04 BST 2011

On Wed, 17 Aug 2011 11:00:48 -0700 (PDT), chris coleman <christocoleman at> wrote:
> On syncs today, OfflineIMAP does things like this: 
> When I move a message, on the local server, from the Inbox to the Trash, offlineimap deletes the Inbox message copy on the remote server, and uploads the message from local server Trash to remote server Trash !  

Yep, that is the expected operation.
> For a 1MB message, that's 10 seconds to upload to the remote server's Trash!  
> OfflineIMAP would run 20X faster/more efficiently if it would *move* the message from the remote server Inbox, to the remote server Trash - a move operation should execute in about 0.5 second.

It would but a) it operates on a folder-by-folder basis (no excuse
though) and b) it is not trivial to detect such moves between
folders. It is not uncommon to have multiple emails with the same
Message-ID in different folders, and they do not necessarily have the
same content. Think e.g. a mail that you sent and that you get back via
a mailing list subscription. It will have the same Message-ID, it will
be in your "Sent" folder and it will be in your "INBOX" folder. Some
broken MUAs are also said to produce identical Message-IDs from time to

Detecting that you actually moved a mail from one folder to another is
therefore no trivial business. The safe bet is to treat these as a
removal and addition in the folders.

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