[Mimedefang] eMail Allowed Sender mechs

[Ben Kamen]

Ok, so I just emailed someone at earthlink and got one of those annoying 
auto-messages that say I have to go through their verification process to get my email
to the subscriber...

Besides the fact I dislike these mechs, the only reason I can think of that they
are bad is that if I ALSO had such a mech, the emails would bounce back and forth
neither ever seeing the need to "validate" against an ISP server.

Any other reasons you folks can think of?

 -Ben