handling IMAP server migration

[Emmanuel Beffara]

Hello,

I am faced with a problem I am sure other people have had in the past.

I store all my work email on my university's servers, this includes archives
back to 2005 and represents roughly a gigabyte of messages. Recently the
university was largely restructured, and this implied a migration to a new email
infrastructure. The IMAP server changed, and so comes the "UID validity"
problem: all messages have changed UIDs. So, basically, I have all messages both
locally and on the server but offlineimap does not know that they are the same.

The proposed "solution" in the documentation
<http://docs.offlineimap.org/en/latest/FAQ.html#what-is-the-uid-validity-problem-for-folder>
is to wipe everything and redownload everything, but it seems a nonsense to
download a gigabyte of data just because offlineimap is unable to figure out it
already has most of the messages.

The missing feature here is a "slow sync" that would involve (for instance)
fetching message-ids from the server, matching them with local files and only
downloading those that do not correspond. Is this possible? I guess this could
be done by hand, by directly hacking the state databases, but this looks like a
dangerous adventure...

Any suggestions?

-- 
Emmanuel