Well...I have a little 2c to chuck in as well
I have just finished designing a system (and implementing it) for our
corporation that allows distributed e-mail across a city, with hundreds,
possibly thousands, of different locations either dialing up or being
permanently connected to our main relay. And all e-mail is sent to
[EMAIL PROTECTED], no subdomains (although we have set it up to allow for
virtual domains in the future), and is delivered to the correct location.
All the e-mail is relayed to NFS shares on client machines around Sydney,
uing Qmail's maildir delivery format. If an NFS share is down (ie a site
hasn't dialed up recently or an ISDN link has failed), then it is deferred
for up to a week - simplistic but it works. All users can check their e-mail
internally from their local server or externally from the main server (only
internet viewable machine in the entire network, and even then through a
router) via NIS.
Why go to all this trouble? You may say. Why not just use aliases? Because
aliases can create excess traffic, bouncing e-mails when servers are down
and the like. The aim of this project was to make network traffic across the
whole network as small as possible, with reliability for as many locations
as possible and the ability for smaller ones to only have to dial in
(similar to UUCP). This way, the only network traffic is an e-mail being
transferred to an NFS share, and all employees are happy. If a server goes
down, no others are affected (except if the master server was to go down,
but even then POP and SMTP will still work, just being deferred until it
comes up again). We are also working on a redundant server for when a link
goes down or the server has a failure.
If you're still reading, congratulations you might be interested in all
this. I am considering writing a HOWTO for this (Reliable and Efficient
Distributed e-mail (REDE) across endless locations) if anybody wants it,
because I have to document it all anyway for the corporation. There might
already be something already out there, I dunno. But it was a great learning
experience for me in Qmail, NFS, NIS, network infrastructure between
locations... If anybody is interested in a HOWTO in the future, please
e-mail me personally.
Regards
Brett Randall
