[Dovecot] Planning a dovecot deployment: issues and questions

Dan Price dp at eng.sun.com
Thu Feb 1 23:44:14 UTC 2007

Hi folks,

I am currently evaluating Dovecot for deployment to ~200 software
engineers (so, heavy email users); I'm hoping this list could provide
wisdom about how best to do the configuration, evaluation and deployment,
and what testing folks have done to determine whether dovecot is right for
their site.  Below I've listed the diffs between the dovecot-example.conf
and our config.

I've been playing with 1.0rc19 running on Solaris Nevada.  We have set it
up on our server on an alternate port from the existing IMAPd, which is
something ancient, horrible and problematic.  We're using sendmail and
mail.local as our MTA and MDA, respectively, as these ship with the OS,
and we need to test them.

I have some users who have volunteered to experiment with the server, and
they are starting to do so.  I've also seen the "flags" problems others
have mentioned on the list, and I do not think I could deploy to
production with that bug affecting the users.

I also have some issues which I'm not sure have been previously reported:
One user (of my 4 test users) is occasionally seeing a bug in which mutt claims to be "[downloading xxx/30724]" headers.  Upon getting very
near to the 30724 total, the total rises to something like: "[downloading
xxx/50132]".  And on and on.  The actual number of messages in the box is
30724.  This is not very reproducible, and we do not yet know if it's a
problem with mutt or dovecot.  Another, using Apple's Mail.App reported:

  "Everything was working fine until i quit out of my mail app (Mac
  mail) and restarted.  Then i saw weird things:

    - messages wouldn't get marked unread
    - messages from eons ago started showing up in my Drafts folder
    - Inbox would keep spinning/loading
    - then eventually Inbox just hung showing me no messages"

Any thoughts about how to approach these issues?  I don't really have a
feel for how to go from user-observed-app-doing-X to imapd-is-doing-Y.

The big challenge for our site may be mailbox size: the median
mailbox size is 62M, the average is 176M and the largest is 1.1GB.
I'd be curious to know what sort of mailbox sizes other sites have
experienced, and how widespread the use of the Dovecot MDA is-- is this
likely to make a big difference for us, and will we have to migrate our
(approximately 25) procmail users to sieve?

Having read the recent discussions about "1.0", I think my team would
really appreciate knowing how to obtain something that was thoroughly
vetted and worked highly reliably.  If major changes are coming, I think
it'd be great to have a 1.0.x stability focused tree, and a 1.1.x (or
2.x.x) feature tree.

Thanks in advance for your comments,


------- ------- ------- ------- ------- ------- ------- ------- -------
[note that IMAPS is off for now, but that's just temporary]

$ diff dovecot.conf dovecot-example.conf 
< protocols = imap
< protocol imap {
<       listen = *:150
< }
< disable_plaintext_auth = no
> #disable_plaintext_auth = yes
< ssl_disable = yes
> #ssl_disable = no
< mail_location = mbox:~:INBOX=/var/mail/%u:INDEX=%h/Mail/imapd-indices
< mail_extra_groups = mail
< dotlock_use_excl = yes
< lock_method = fcntl
< # dp: we'll see.
< mbox_read_locks = dotlock fcntl
< mbox_write_locks = dotlock fcntl
------- ------- ------- ------- ------- ------- ------- ------- -------

Daniel Price - Solaris Kernel Engineering - dp at eng.sun.com - blogs.sun.com/dp

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