Esoteric network setup question

[Chuck Swiger]

William Palfreman wrote:
[ ... ]
 > I have found that fetchmail and sendmail reject mail in the form
 > <username at tld>, where tld is a top level domain resolvable using the
 > correctly configured LAN (primary master) nameserver, with a correct
 > MX record.

You need to tell the MTA which domains should be considered local.  In 
the current context of FreeBSD and sendmail, try adding domain.tld to 
/etc/mail/local-host-names.

 > Personally I consider this a bug, but I haven't got round to
 > identifying exactly where it occurs.

It becomes very hard for software to correctly determine what the user 
really intends when people expect contradictory things.  For instance, 
right now, MTAs assume that they should perform local delivery for the 
local systems' hostname, which is now defined more or less as "the set 
of hostnames I get by performing reverse DNS lookups on all of the 
configured network interfaces".

If the MTA also did local delivery for it's parent domain by default 
(expect a hostname of 'host.domain.tld'), and someone named a machine 
without a host-part, Bad Things happen.

 > Since then I've switched to using the form host.lan.domain.tld,
 > largely because I'm planning to setup legitimate IPv6 DNS for them.

I just set up a site to be W3C P3P-compliant for presumably similiar 
reasons.  There is a certain satisfaction from organizing things to work 
the way they should, regardless of whether anyone else will notice.  :-)

-- 
-Chuck