[Dovecot] Questions still about a uw-imap -> dovecot conversion

Joseph Tam jtam.home at gmail.com
Tue Feb 21 02:25:46 EET 2012

Steve Campbell wrote:

> The more I read about all of this, the more I'm thinking about moving to 
> maildir format. My switchover this weekend is full of holes due to the 
> way user's imap folders were laid out. Some had folders in their home 
> directory and others might have folders in their /home/mail directory.

I had the same problem, and handled it more or less the same way as
the later poster (Jim Lawson <jtl+dovecot at uvm.edu>) handled his site.
I retained use of mbox format as well.

I planned the migration like this

 	- scan user home directories for mailboxes (especially "Trash",
 	"Drafts", "Sent", etc.) looking for "From " as the first 5 bytes.

 	This was piped into a script that Email'd users about the changes
 	that was going to happen, what they would expect to see, and a
 	FAQ on how to set up a mail client correctly.

 	- during the cutover,

 		- mailboxes left on the home directory were moved to
 		~/mail, or renamed (e.g. "Sent" -> "00Sent" to avoid
 		name collision for users that had a mixture of correct
 		and blank prefixes.

 		(I think I deleted "Trash", "Junk", etc. anyways).

 		- Namespace aliasing was used so that prefixes "", "mail",
 		"~/mail", and whatever darn fool settings my users used,
 		would map to the same directory.

 		- .subscription files were moved into the mail folder
 		(don't have to edit prefixes since the aliasing
 		will take care of that).

 		- depending on what POP3 client you used (I used
 		qpopper), you may need to configure

 			pop3_reuse_xuidl = yes

 		to avoid a massive re-downloading from POP3 clients
 		after cutover.

 		- the mail clients I control centrally (e.g. webmail,
 		public server mail clients, etc). shouldn't need updating
 		since they ought to have been set up properly in the first

 	- after cutover, a second notification was sent for users that
 	didn't move their mailboxes the first time around, and was it
 	done for them during migration.

And of course, test like crazy and watch the logs like a hawk.

Other gotcha's:

 	- your setup is fairly close to mine, so you may also run into
 	the problem of user having mailboxes with group ownership that
 	users are not part of (for example, group "mail" for INBOX set
 	by your LDA or personal mailboxes with groups the user is no
 	longer a member of) *and* with group permission not mode=0.

 	You'll have to treat these (set mode=0, or change the group to
 	something the user is part of), or the dovecot index creation
 	will fail and they won't be able to access their mailboxes.

I think my migration went pretty smoothly.  Less than a handful of wazzup'
Email problem reports.

Joseph Tam <jtam.home at gmail.com>

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