Outbound and Inbound mail on same server

[Julian Field]

I am a definite fan of having incoming and outgoing mail on completely
separate servers. Having incoming and outgoing on the same servers just
seems like too many jobs on 1 server. Hardware is cheap, service loss is
expensive. Here I run 2 incoming servers, a bunch of internal ones which
deliver peer-to-peer, and 2 outgoing servers. Each half of the pairs are in
different buildings and run from different power company sub-stations.

So everything is multiply redundant, I can take out either of the incoming
or outgoing servers at any time without loss of service to anyone. If I
need to take both outgoing servers out at the same time (which hardly ever
happens anyway) then no-one loses any SMTP service, the incoming and
internal servers just queue it all until the outgoing servers re-appear.
FYI this is a sendmail-only setup (which is why MailScanner supported
sendmail first
:-)

The same setup has done us well for many years now. I re-wrote it all from
scratch back when the UK joined the Internet for the first time, but
haven't really touched it since other than to add support for multiple
domains, virtual users, stuff like that. Major mail outages just don't
happen. Not ever.

Just my 2p worth...
--
Julian Field
www.MailScanner.info
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