[gerdesj]

Exim has a rather mad ACL etc system which is what I need. Postfix is absolutely ideal for receive mail, pass to AV/spam checker, pass it on (or not).

Exim is hugely configurable. If you use it on Debian/Ubuntu and you have somewhat complex needs then ditch the split config thingie and simply create your own /etc/exim4/exim4.conf from scratch.

You can test a config with "exim -bhc <ip.add.re.ss>" to simulate a SMTP session from <ip.add.re.ss>, before you restart Exim to make the config active. So:

  helo me
  mail from: [e-mail]
  rcpt to: [e-mail] 
  data
  etc etc

At each stage you get a debug output of what would happen. You have to be a bit careful with this because a new Exim daemon will use the new config. For small changes do it "inline", for major changes, copy the conf to a new name and specify it with -C and test until it works. There are a lot of options.

Documentation is complete for Exim. If you find a flaw then Jeremy and co will fix it - the Exim devs are very, very driven, for want of a better word. You will get short shrift on the mailing lists if you obviously haven't tried to do any research but you will soon get some extremely knowledgable help if you show willing. No Disqus etc - just old school mailing lists and that is the way it should be.

The big boys are destroying SMTP gradually but it can and does still work, if you are careful.

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