Re: big mailer

[Jeff Licquia <jeff@luci.org>]

On Thu, Apr 06, 2000 at 09:32:38AM -0500, Cloudmaster wrote:

> Hey, do any of you have any experience with (implementing, using, searching
> for, etc) a "more efficient than mbox" mail storage format?  We're setting
> up a web-based e-mail system for about 20-30,000 students (initially) that
> wil also provide IMAP and POP service, but no local readers.  I know that
> using a big damned text file is not the best way to do things if it's
> avoidable, and since it IS avoidable, I was wondering if any of you had any
> other suggestions.

Warning: I've never implemented IMAP/POP3 on this scale before, but
really, I play a sysadmin on TV... :-)

Those whom I've read who seem to know all seem to think that maildir
is the way to go for really high-volume mail services.  For MTAs that
support maildir, a lot of these people are also very keen on qmail as
an MTA, although there's a small but growing contingent that are
liking postfix just as well or better.  (Personally, I like postfix -
I'm using it at home and at work.)  But, I think you can configure
sendmail to use maildir as well.  More info on maildir can be found at 
http://www.qmail.org/man/man5/maildir.html.

> I'd also like to know if any of you have played with both Cyrus and WU imap
> servers (those both do POP too, right?), and if there's any real strong
> opinions as to the performance of either - or even strong opinions as to
> alternatives.  I seem to have gotten the impression that with Cyrus it'd be
> easier to create mail accounts without having to create system accounts, is
> there any truth/merit in that?

Cyrus is without a doubt the higher volume system.  Its design mimics
inn for news, which can handle very high loads.

In this day and age when just about anything can be done with PAM and
NSS, there isn't much difference difficulty-wise using non-system
accounts on UW imapd vs. Cyrus.  Cyrus is cleaner in implementing some
of IMAP's features; for example, Cyrus doesn't try to fit home
directory folders into the IMAP system like UW does.

Cyrus's main disadvantage is its license.  It specifically forbids
commercial use unless you're an ISP (go figure).  Also, Cyrus doesn't
play well with other software.  Its mail directory format is all its
own, and not all MTAs support it.  It might also be hard to get
documentation for to parse it on the web end; this could force you to
write your web front end to query via IMAP, which could affect
scalability.

You might also want to look at Courier IMAPD, at 
http://www.inter7.com/courierimap/.  It's a server designed
specifically for providing IMAP services to Maildir mail spools, with
an open spec for writing auth modules and some other nice features.

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