The index files are my main concern.
Courier will ignore them. So they may be out of sync if you move a lot of messages around with Courier, but Dovecot will update them.
I guess the safest thing to do is to tell postfix to queue his mail so nothing gets delivered while he's messing around, then let him play - see how fast folders load, etc (he's got some pretty big ones, 30,000 messages or more)...
The safest thing to do, of course, is to back up.
Of course - which is why I said that would be the first thing I did... ;)
Thanks - I'll wait and see if anyone else chimes in - I like to get more than one opinion, and to hear from at least one person who has actually done what I'm about to do, when trying something like this (that I've never done before)...
I've done similar, my mailstore is on nfs, and had completely different servers both accessing it. And yes, Dovecot was much much faster.
Good to know - thanks for the contrib... :)
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Best regards,
Charles