> > RFC 2006 <http://tools.ietf.org/rfc/rfc2606.txt> indicates you are right.
> > I need to do some testing. Maybe I jumped to the wrong conclusion why
> > specifying "localhost" only causes problems.
> reject_non_fqdn_helo_hostname will catch a bare 'localhost' since it has
> no '.', but 'localhost.' doesn't work either, since the implementation
> specifically checks for '.' within the string. So it'll cause problems
> here either way, but...
> I'd say that's a mistake, and not one amavisd-new should be trying
> particularly hard to avoid. On my systems, I reject any HELO coming from
> the outside that looks like localhost, the box's own addresses or domain
> names, the RFC 2606 reserved names, and a handful of common pseudo-TLDs,
> including '.localdomain'. But it's perfectly fine to use 'localhost' over
> the loopback:
Well, so far the 'localhost' seems to have caused least surprises.
Initially the default was to use $myhostname, but that caused Postfix
to complain about mail looping. I agree that 'localhost.' may indeed
be a little bit better choice - but in the absence of 'search' or
'domain' in /etc/resolv.conf (at the MTA host) they are both the same.
Not sure if it is worth changing the defult, considering that the
reject_non_fqdn_helo_hostname will reject either.