[Mimedefang] Adding support for learning our addresses

[Damrose, Mark]

> -----Original Message-----
> From: Philip Prindeville

> Damrose, Mark wrote:
> > since 
> >the internal and external DNS for my namespace are maintained on 
> >separate servers.
> >  
> Not if you query one of the root name servers...

Ignoring for the moment, that even if the root name servers would
do DNS resolution for you (they won't), that would be an abusive use
of them.

If you mean change /etc/resolv.conf to use a DNS resolver that knows
about the external name space, my mail server knows about my internal
name space for a reason.  In fact there are about 2000 reasons - whose
name to IP address mapping I am not about to put into a public version
of DNS, but my mail server needs to know about.

If you mean use Net::DNS and force it to query a server that knows about
the outside name space, I was under the impression that your goal was
to be portable across systems with no changes, and to publish it as 
such for others to use.  If you have to do those kinds of customization,
I don't see why 
my $ipaddress='ip.add.re.ss'; 
is a huge problem.

> in /etc/mail/local-host-names.  Why not read 
> >that file?
> 
> Gak.  Then we're relying on its format staying the same,

It has for a number of versions of sendmail.

> and 
> second that we need to be able to parse the file.

# starts a comment
domain name or [ip.add.re.ss], one per line.
You'd be hard pressed to find anything simpler to parse.

If you accept mail for more than one domain locally, you need to 
customize this file anyway.  RFC (and the STD that incorporates
it) state you must accept mail at the domain literal.  If you
NAT, you must customize this file to do that.