On Wed, Mar 17, 2010 at 12:43 PM, Tony Rutherford tony@bluetie.com wrote:
On 3/16/2010 7:36 PM, Timo Sirainen wrote:
On 17.3.2010, at 1.01, Mark Moseley wrote:
- Since Dovecot 2.0 seems like it's just around the corner, that's all I've been testing, and indeed all I've even looked at.
Yes, hopefully it's coming soon :)
- Our #1 main motivation for looking Dovecot is relief for our currently overtaxed NFS servers, mostly in the form of the index files. Benchmarking dovecot looks great, even with the index files in the maildir.
Have you read the thread starting from http://dovecot.org/list/dovecot/2010-January/046106.html and spanning a month or so? That provides a good view of potential problems with NFS.
- Exim: We currently deliver all of our mail via Exim on separate servers. Our POP3/IMAP servers only do POP3/IMAP and the Exim mail servers delivering to maildirs only do Exim. From what I've seen in the docs and various threads, from what I can gather, the best thing to do in that case would be to use Exim's built-in maildir handling, instead of using 'deliver'. That would be my preference anyway, but I wanted to make sure I didn't misinterpret things.
v2.0 supports also LMTP server, so you could deliver to Dovecot that way.
- Any problems running Courier POP3 and Dovecot IMAP for a while, possibly Courier IMAP and Dovecot IMAP concurrently?
Courier POP + Dovecot IMAP is fine. But concurrently running both POPs or both IMAPs is just going to cause trouble because of conflicting UIDs. You might be able to make both Dovecot and Courier use the same POP3 UIDLs, but I wouldn't really trust it.
One possibility would be to just run the migration script on login, so users would migrate to Dovecot as they log in.
I would add a big warning as well to running Courier and Dovecot concurrently. If users are strictly segregated to using one or the other (consistently), then strictly running Courier and Dovecot on the same machine is not an issue (on different ports or whatever). But, I would NOT recommend having it such that a user could hit Courier one time and Dovecot another...I think that is begging for big trouble. As Timo mentions, most of the trouble will be with syncing the UIDs. Even running POP Courier and Dovecot IMAP might be a problem...especially if your users can use both POP and IMAP....Courier has 2 uidl files, (at least the version we were migrating from)..one for POP and the other for IMAP, and they get combined to one in Dovecot (dovecot-uidlist). Then if a user comes in via Dovecot...and updates the dovecot-uidlist...by definition the Courier files would be out of date. I would really steer away from that approach.
I'll definitely keep that in mind. I should be able to keep things pretty segregated in terms of POP3 alone or IMAP alone but my big worry is that Courier POP3+Dovecot IMAP scenario. I'm thinking especially of people using POP3 in one place and webmail in another location. I'm guessing that people using POP3 in one location but direct IMAP in another are fairly rare. Whatever the case, it sounds like I need to do some log analysis to see what % of people access in both ways. Thanks for the advice!