the X-OfflineIMAP header

Johannes Stezenbach js at
Thu Nov 25 17:28:17 GMT 2010

On Thu, Nov 25, 2010 at 11:25:00AM -0500, Dan Christensen wrote:
> But when an article arrives at the local IMAP server and is synced to
> the remote server, both copies get an X-OfflineIMAP header.

What do you mean by "arrives at the local IMAP server"?
Unless I'm mistaken offlineimap only adds the X-OfflineIMAP header
when it STOREs messages to an IMAP server.

> is a problem, because in order to do this, offlineimap must delete the
> local message and create a new message (with a new UID).

The X-OfflineIMAP header is only added on the fly during the STORE
command, not to the source message.

Note that I've never used IMAP -> IMAP sync, only IMAP to Maildir, so
maybe I just don't understand the issue.  I'm guessing offlineimap
is using ~/.offlineimap/Repository-foo/UIDMapping/ to keep track
of message identity between both IMAP servers?

> 2) For IMAP servers that support UIDPLUS, it shouldn't be necessary to
> insert the X-OfflineIMAP header at all, since they return the UID of
> the APPENDed message using the APPENDUID response code:
> The number 10732 is the UID of the newly created message.  No need
> to alter the message with a header or to issue a separate SEARCH
> command.

Sounds good.  Would be nice if someone could implement this.


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