Documentation of big "mail systems"?

[Jo Geraerts]

hi,


On Tue, Oct 12, 2004 at 11:20:51PM +0200, Stephane Bortzmeyer wrote:
> I'm currently writing a proposal for a webmail service for, say, 50
> 000 to 500 000 users. I'm looking for description of existing "big
> mail" systems, using technologies like scalemail
> (http://scalemail.sourceforge.net/), specially with an emphasis on the
> storage subsystem for the servers (my weak point, I don't really have
> enough experience with SAN, NAS, and so on).

i would seriously consider a qmail-ldap system as backend. Especially the
clustering feature is very nice. With this clustering you can simply use
off-the-shelf hardware and balance the mailboxes over the mailstores (
as i call them.)

a mail may enter the cluster at any system and it will be queued on the
right system. qmail-ldap has also a password check for courier-imap
which redirects the imap session to the right mailstore. so it behaves
as a single system with lots of mailstorage but you don't need pricy
nas/san systems. Another advantage is that it scales pretty good since
you dont have a single point ( like a nas) where everything comes
together.

i've a mail setup with 1 MX server, 2 mailstores and a relay server
which servers about 130 000 people with simple commodity hardware: dual
p3, 1 gig mem and 2 IDE harddisks. The dual processor is a little bit
oversized but we use the same server for everything.

if you want advanced filtering and anti-spam features, put
postfix/exim/... in front of the qmail-ldap cluster. ( qmail-scanner is
so not done on large systems, since it requires a perl invocation per
connection)

As webmail i use squirrelmail, but i think i made the wrong choice. The
problem with this setup is that it makes a imap connection for every
pagerequest. If I had to redesign a new webmail system, i think i would
use something that supports persistent imap connections ( some kind of
servlet or zope application)

best regards,


jo

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