We're an ISP with approximately 9000 email customers. Up until early
in January our primary mail servers ran on OS X, with exim as the MTA
and courier-imap as the pop/imap server.

We had continual problems with courier on OS X. The load it
generates on the machine is horrible. You'll get absolutely no help
from the courier mailing list or developers with OS X issues.

When we started evaluating Dovecot, we first attempted it on OS X,
however we were unable to get it running in an NFS environement on OS
X in any sort of stable manner.

I can't recommend highly enough getting off of OS X if you can for
mail services. We went to Red Hat machines, and they have been
amazingly stable and reliable. I love OS X, and use it for other
things, but it makes a bad mail server at least for the volume of
mail we process.

-- Roger J. Weeks Systems & Network Administrator Mendocino Community Network

On Mar 26, 2006, at 12:24 AM, dovecot-request@dovecot.org wrote:

Message: 2 Date: Sat, 25 Mar 2006 09:22:18 -0800 From: Dean Blackburn <dean.blackburn@viz.com> Subject: Re: [Dovecot] OS X-centricities? Too many files, temp, indexes, etc... To: dovecot@dovecot.org Message-ID: <44257C4A.6030801@viz.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Timo Sirainen wrote:

...

...

1. Too many files open - no plimit command on OS X, so I can't
   figure out how to increase the max number of open files... Also, are
   there any alternative means of CLOSING the files? stopping/restarting dovecot didn't seem to help;

Which process is running out of them? There are multiple Dovecot processes, and each could have a different reason of running out
of file handles.

dovecot: Mar 24 11:35:51 Error: imap(yukimurashige): pipe() failed:
Too many open files dovecot: Mar 24 11:35:51 Error: child 21465 (imap) returned error 89

...

...

2. I was running 1.0beta1 last week, and am now on 1.0beta3, but I'm still not seeing corrupt indexes/other dovecot files rebuilding themselves. I really can't stick with this solution if I'll
   always have to worry about manually fixing broken caches/indexes.

First of all they shouldn't anymore be corrupting themselves at least easily. What exactly are the error messages you're seeing?

Lots of this:

dovecot: Mar 24 12:18:45 Error: imap(mikitanaka): Corrupted index file /Users/mikitanaka/Maildir/dovecot.index: uid_validity = 0, next_uid
= 1366

Some of this:

dovecot: Mar 24 10:55:45 Error: imap(kristinegivas): imap(19936)
malloc: *** error for object 0x602200: incorrect checksum for freed object - object was probably modified after being freed, break at
szone_error to debug

And occasionally this:

dovecot: Mar 24 11:00:14 Error: imap(deanblackburn): Maildir /Users/deanblackburn/Maildir sync: UID inserted in the middle of
mailbox (1042 > 1041, file = 1143071249.Ve000008I8e7f3b40.mailserv.local:2,Sk)

That's just yesterday's errors, we've seen some others as well. But
they all go away if one deletes dovecot* from the affected directory, and they don't go away on their own. Also, we'll see a huge number of
temp.* files build up within the maildir once these files "go bad"...

From the client perspective, you either get a "connection timed out" error, or on some less robust clients, "connection refused by IMAP
server".

...

Also as far as I know they're rebuilding themselves automatically in most situations. Only if Dovecot crashes because of the corruption it doesn't get rebuilt. If it's not crashing with you, could it be just that they keep re-breaking all the time?

Definitely possible. ;) How can we tell?

If we can solve these issues, we'll be very happy with Dovecot... Courier seems a lot more solid, in retrospect, but required so much
disk access it was completely unusable by our staff. In contrast,
Dovecot is fast, light on resources, but will break around 5-10 individuals' mailboxes every day. So far, we just can't win!

-deano