Migration - Getting it right the first time.

[Dan Carroll]

Hello All,

I’m currently in the process of migrating a very old imap installation to a new server.
I think I have everything in place now but I’ve not yet written the procedure on how to do it.

The outline will be as follows:

put MTA-OLD into store mode where it holds the incoming emails for an indefinite period.
Copy all IMAP data across to the new server.
Process the IMAP data, converting it from courier to dovecot.
put MTA-OLD into forward mode, sending all mail to MTA-NEW
Adjust MX records accordingly so MTA-OLD is no longer used.

The “process” part is where I need to take some care.

I am aware of the migration tool available for moving the data, but I’m not confidant that my courier databases are in a healthy state.

Does anyone have any idea how I can verify that this is the case?   I’m happy to do it either before, or after the migration to dovecot, but I’d probably prefer to do it beforehand on the old server.

The biggest thing I am concerned about is losing the order of mail messages.   It’s not always enough to trust the “received date” for sorting mail, I’d rather my imap clients trust the imap server to send them the correct order.

A second question.   Is there a possibility to make the MTA switch, and migrate the messages across in an orderly fashion at a later date?   Again, I’d like to ensure that older migrated messages appear further down the “order” than new messages coming into the MTA.

Lastly, thanks for an awesome piece of software.   My limited experience so far has been refreshing!

-Dan