Re: [Exim] use of _ in HELO... again

On Fri, 22 Aug 2003, Wakko Warner wrote:

> I've run into a problem where I've been told by management to break the RFCs
> and allow the use of _ in an HELO.

I can sympathise with you being leaned-on to do that. Indeed we've
got a (rather) short list called helo_accept_junk_hosts, of IPs from
which it was politically expedient to accent broken HELOs. I see that
*.house.gov is in there... bleagh.

But when you do it as a matter of course, then from our point of view
you become part of the problem rather than part of the solution.

The "defer" verb can be a useful measure for things you don't like but
might be forced to accept. Let them stew for a few hours, or a day or
two, retrying at intervals while you get around to deciding whether
you can get away with rejecting them, or will have to accept them;
then adjust your configuration accordingly.

One thing that this Sob*g virus incident has reminded me about, is
that viruses with their own SMTP engine don't re-try, so it can be
very beneficial to respond to the first try of any dubious mail offer
with a defer, even if you accept soon afterwards ;-) That's just
another flavour of "greylisting", I guess.

> I sent them the relative RFCs about this. They came back with "RFCs aren't
> standards".

Ah, the answer that I once got was "that's what Microsoft does, so
it's obviously correct".

> Anyone have any thoughts of how to combat stupid management?

Sorry, that's our Achilles heel.