dovecot - Jan 2009 - Dovecot suggestions for new installation

I've been testing Dovecot for a while now and am preparing to replace  
our outdated IMAP
system with it. The current system serves about 300 email users who  
run a mixture of
clients (Eudora, Apple Mail, Thunderbird and Outlook). Can any of the  
many experts on
this list answer a few questions:

     1) What's the latest stable release of Dovecot I should be  
running on this new system
          (Dovecot will be running on a RedHat Linux AS 4 64 bit  
system with plenty of memory
          and CPU). I've been running 1.13 on my test system but I see  
that 1.18 just came
          out (although I don't know if I should switch to it  
immediately.

     2)  What configuration file options (if any) should I turn on to  
best handle the range of
           email clients listed above?

     3)  Are there any "sizing" options I need to worry about setting
for the number of
           email users I have (I suspect that 300 users is considered  
a rather small
          mail system but I want to minimize its resource usage as  
much as possible
          while still giving decent performance from Dovecot).

    And, just out of curiosity, I'm looking into the idea of switching  
users from mbox format
over to Maildir format on this system (it will use all locally- 
connected disks and have no
NFS mounts). Does the Dovecot automatic migration program to migrate  
from mbox
to Maildir work well or are there "gotchas"?

    Thanks.

On Jan 13, 2009, at 10:45 AM, Michael Durket wrote:
> I've been testing Dovecot for a while now and am preparing to  
> replace our outdated IMAP
> system with it. The current system serves about 300 email users who  
> run a mixture of
> clients (Eudora, Apple Mail, Thunderbird and Outlook). Can any of  
> the many experts on
> this list answer a few questions:
>
>    1) What's the latest stable release of Dovecot I should be  
> running on this new system
>         (Dovecot will be running on a RedHat Linux AS 4 64 bit  
> system with plenty of memory
>         and CPU). I've been running 1.13 on my test system but I see  
> that 1.18 just came
>         out (although I don't know if I should switch to it  
> immediately.
I recommend 1.1.8. Especially if you're planning on using mbox format,  
since it fixes several bugs related to it.
>    2)  What configuration file options (if any) should I turn on to  
> best handle the range of
>          email clients listed above?
Look at the imap_client_workarounds setting and enable the ones you  
need.
>    3)  Are there any "sizing" options I need to worry about
setting
> for the number of
>          email users I have (I suspect that 300 users is considered  
> a rather small
>         mail system but I want to minimize its resource usage as  
> much as possible
>         while still giving decent performance from Dovecot).
Not really. The default options should be fine for that. Anyway see
http://wiki.dovecot.org/PerformanceTuning
>   And, just out of curiosity, I'm looking into the idea of switching  
> users from mbox format
> over to Maildir format on this system (it will use all locally- 
> connected disks and have no
> NFS mounts). Does the Dovecot automatic migration program to migrate  
> from mbox
> to Maildir work well or are there "gotchas"?

It doesn't preserve message UIDs, which causes clients to redownload  
them. This isn't such a big deal with IMAP, but if you have any POP3  
users that could be a problem (although you should make sure  
pop3_uidl_format is correct in any case).

I'd anyway recommend using one of the scripts that preserves UIDs,  
just in case. http://dovecot.org/list/dovecot/2008-March/029736.html  
apparently should work.

Also you should configure Dovecot to use '/' as the namespace  
separator for maildir too. Some clients don't like it when the  
separator changes unexpectedly. Also the '/' is more
"standard"
anyway. You might also want http://wiki.dovecot.org/Plugins/Listescape  
to allow using '.' characters in mailbox names, which you might  
already have.