[Mimedefang] MX -> 127.0.0.1

[Kevin A. McGrail]

I hadn't seen it but it's good code and more functionalized than my code.
However, it's missing the issue that while CNAMEs are not RFC compliant,
people do use them.  And I also found a bug where the MX resolution is
supposed to be returned in preference order but it doesn't seem to be done
so in reality.

KAM

> Have you seen this code:
>
> http://www.mimedefang.org/kwiki/index.cgi?CheckForMX
>
> Perhaps this wiki page is not sufficiently generalized, as this is another
use of some of that code?