[Mimedefang] MX -> 127.0.0.1

[Kevin A. McGrail]

> Exactly. If you need different MX for both inside and outside users, set
up
> a split DNS. for the inside users, they ask an internal DNS that answers
with
> the internal IPs. The external users query a public DNS that answers with
> public IPs.
>
> It's easy to set up and solves a bunch of problems. There's no excuse for
> publishing RFC1918's IPs in a public DNS

I'm not arguing it's right or good, I'm simply saying it's commonplace and
will cause false positives.

I'm also not sure yet if I would use this to reject or discard emails.  That
code (based on Joseph Brennan's) is coming later.

Regards,
KAM