Building a SMTP Relay (Domain MX/Smarthost) with Exim

[Geoff]

I'm in the process of rebuilding our mail relay as it's hard drive exploded. I'd decided to go with Exim this time round as I found Postfix's obsession with security highly annoying and counter productive for the servers role.

This situation is slightly complicated from a vanilla MX as there's some specific mail routing issues I need to overcome.

1. I have two internal mail servers. An exchange 2003 server for staff and a Zimbra server for the kids. I need to route in/out to these servers and between them correctly.

2. By default I want to deny inbound/outbound non-local mail on a per account basis.

Also, I'm using the Ubuntu Exim4 package. Which is based on the Debian package. This uses complex non-standard configuration system. At first glance it seems over engineered for my needs. So I'm wondering if I should throw it away and do a vanilla configuration from scratch.

So I'm wondering if anyone has done anything along these lines? I'm currently digesting the Exim docs so I can probably figure it out given time. But any pointers would save me time and effort.

[CyberNerd]

how about using Zimbra as a relay for excahnge? - you get to loose a box that way and can do spam/content filtering there. Theres an article here: http://wiki.zimbra.com/index.php?title=Split_Domain although I have not implemented it yet (or exim)

[Geoff]

Ok, that solves problem one. However I'm still stuck with problem two...

[Geoff]

Further investigation reveals that Exims ACL system can stop delivery of mail based on the sender and/or recipient portion of the mail address. Debians config system provides some infrastructure to do this quite easily (now I've found it in '/etc/exim4/conf.d/acl/20_exim4-config_whitelist_local_deny'').