- setup a testing machine with iRedMail-0.8.3 on CentOS 5.x (so that it will install Dovecot-1.x)
- upgrade Dovecot to 2.0.x by following this tutorial: http://wiki2.dovecot.org/Upgrading/2.0

Looking for the best way to do a migration instead of an upgrade.  My production server currently has 86 domains and about 400 users, and I don't want to move any more to it till I solve my issue.

After fighting with trying to get "expire-tool" working for months, I am thinking that the best way to deal with it is just to upgrade to Dovecot 2.0 so I can use doveadm expunge (because my users aren't good at emptying their Junk and Trash).  Problem is that I am running this on CentOS 5.6, which doesn't support it out of the box.

So, what I am thinking is, instead of doing an in place upgrade, to instead set up a new server running CentOS 6.2 (or whatever is the most recent) and installing a fresh iRedMail and iRedMail-Pro on it.  Then, move the domains and users from the old to the new.

I'm looking for the least problematic way to do this.  When I migrated users from our old SmarterMail server to iRedMail 0.7.3, I set up the domains and users manually on the iRedMail server and then used Thunderbird IMAP to move one user account at a time (there is a lot of mail stored on the server).  Is that the most reliable way, or can I shortcut the process somehow by copying files, etc?  It looks like there are a lot of MySQL changes and I don't want the server down while I figure them out.  The fresh install looks like a cleaner way with less issues to pop up, but it is going to be a LOT of work to move all the users.