Recommended Dovecot / Thunderbird to Exchange / Outlook Migration Strategy

The best way to go is using imap!

You COULD let each user move the messages himself by giving him both accounts in Outlook.

I did a migration from Cyrus to Exchange 2003 using a separate linux box with the Debian package "uw-mailutils" and this command:

mailutil transfer -verbose {imap.xxx.org:143/imap/user=m_xxx}INBOX {exchange.xxxx.org:143/imap/[email protected]} INBOX

mailutil is from the UW-IMAP project. Every Linux distro should contain it.

When it failed (which it didn't) I would just go into the exchange account and delete "INBOX"

I've done many such migrations on much larger systems; 300+ mailboxes and I've migrated in many directions: Courier -> Cyrus, Exchange -> Cyrus, Courier -> Exchange, and Cyrus -> Exchange...

Our tool of choice is called imapsync; an open source Perl script. It uses the actual IMAP protocol to handle migrations thus alleviating the need to deal with underlying specifics to each implementation (aildir formats, mailbox annotations such as DONT (.) vs. slash (/) seperators.

IMAPSYNC is also re-entrant safe. You can run it multiple times over the same accounts and it will only copy what has not been copied the first time through or any new emails that may have arrived.

We typically dump all the user accounts to a BASH script that, in the end, is executed like so:

./imapsync --host1 mail.pozicom.net --user1 someone@domain --password1 mypassword \
           --host2 localhost --user2 someone@domain --password2 mypassword

Where host1 is where you're copying from host2 is where you're copying to.

You can get IMAPSYNC from here: http://freshmeat.net/projects/imapsync/

I've used the "imapsync" program before to mmigrate from an IMAP server to Scalix (an Exchange-like system). Think rsync for IMAP mailboxes.

Jim.

We have a huge large mail system, and routinely ingest users from other mailsystems (typically Notes or Groupwise). One common thread in all of these migrations is that the data migration piece is always a disaster. There are always intractable problems, VIP issues end up taking priority and the normal user population suffers. Migration tools have bugs that never get fixed because nobody does a Notes->Exchange migration twice!

What we're looking at for a future strategy is a mostly greenfield mailbox, with users identifying email that must be retained. For you its easy -- keep the dovecot servers running for 6 months, setup Outlook profiles pointing to the old imap system (I believe this is scriptable with Outlook 2007) and let users migrate in their own time.

You'll find that most folks really don't need what they say they need, and after 6 months, any legit need to move data to the new system will be done.

Another option is to use a mail archiving solution. We have to archive all email due to litigation, and oftentimes you can "ingest" messages from an old system into a hosted archiving solution. Check out Postini and Microsoft Hosted services.