[Mimedefang] MX -> 127.0.0.1

[Les Mikesell]

On Tue, 2005-09-13 at 09:25, Kevin A. McGrail wrote:
> > } However, right now, I am thinking I should be able to do the invalid
> helo
> > } and invalid MX check in filter_sender since I have $sender and that's
> all I
> > } need.  If I reject in filter_sender, I haven't received the entire email
> yet
> > } and it isn't a very "costly" transaction.
> >
> >      If you do the test in filter_sender() then a discard would
> > definitely be more expensive since that would force you to receive the
> > message; whereas with a reject you wouldn't even have to look at the
> > recipients much less receive the message.
> 
> I am looking more towards using these tests in filter_sender and if they
> fail, to return a 5XX level Rejection for Invalid MX Record so I think we
> are on the same page.

If the only or best MX target is 127.0.0.1, this is fairly hostile
toward your neighbor relay.   But, as I mentioned before, the spam
appliance I am forwarding through is doing a 451 temp_fail which
just prolongs the problem and backs up my queue.  There's no chance
that a notification is going to make it anywhere in this case
so why not drop it?   On the other hand if there are multiple
targets and some appear good, it might make sense to reject/bounce.

A logical extension of this would be some way to parse your logs
for repeated failures for bounce delivery attempts and add those
to the bad address list.

-- 
  Les Mikesell
    les at futuresource.com