[CentOS] Converting to maildir

Tue Jan 4 15:51:47 UTC 2011
Les Mikesell <lesmikesell at gmail.com>

On 1/4/2011 9:38 AM, Jeff wrote:
>> Here are our relevant specs.
>> sendmail-8.12.11-4.RHEL3.6 (we may not be able to upgrade this due to too many
>> modifications)
>> imap-2002d-14
>> procmail-3.22-10.el3.centos.0

> Regardless of the maildir vs mbox argument, I would be seriously
> examining why you have painted yourself into a corner with your
> customized sendmail. Eventually, you will have to move on.

Errr, why???  Sendmail has nothing to do with local deliveries.

> What are
> the motivations for the customizations? Do newer or alternate MTAs
> have added features that can replace those customizations? Postfix can
> be highly customized through configuration and is not that difficult
> to learn.

Why change the part that isn't broken.

> As a migration path, I would separate the MTA (sendmail) and the imap
> server. Go with cyrus or dovecot on a new machine (virtual?) and use
> imapsync to move messages to the new box during a maintenance window.
> As stated in other responses, cyrus has it's own mail storage format
> with individual files for each message and dovecot supports several
> formats including maildir. It should not be difficult to have your
> existing sendmail deliver messages to the new imap store either
> directly or with a very simple postfix MTA on the imap box. Once mail
> storage is fixed, you can start working on de-customizing your MTA.

Sendmail will let cyrus or procmail or another local delivery agent 
handle the file format details - and probably already does.

> And with regard to backup space, it might be time to suck it up and
> tell your users that you need to implement mail quotas. How much are
> you backing up from "Sent" and "Trash" because nobody maintains their
> mail folders? A quota can be a great tool for teaching basic mail
> folder housekeeping.

Anything that does sensible incrementals will use much less space with 
'file-per-message' formats instead of mbox because the bulk of the 
messages won't change between runs.   But maybe another solution would 
be to put the backups on a block de-duplicating filesystem like zfs.

   Les Mikesell
    lesmikesell at gmail.com