Re: HELO/EHLO and applicability statement

Yakov Shafranovich wrote:
> 
> Raymond S Brand wrote:
> >
> >>  The hope that people will use FQDN's is contentious, of course.  To
> >
> >
> > Most of the legitimate SMTP connections I see have had FQDNs in the EHLO
> > command.
> >
> 
> Do you mean to imply that IP addresses will not be allowed in the HELO
> command? Is there a conflict with between saying this and RFC 821/2821,
> in particular section 4.3.1:

I'm not saying anything but FQDNs in the HELO command are forbidden. I made
an observation that most of the legitimate (non-spam, non-virus) mail that
made it into my archives seemed to have come in on an SMTP connection that
had a FQDN HELO parameter. Some friends with busier mail servers saw the
same when they checked for me.

So the hope that people will configure their MTAs send FQDNs in the HELO
command may not be all that contentious, at least on their main outbound
gateways. Local connections are another matter entirely.

DRIP only works with FQDNs. Local policy MAY dictate that non-local, non-AUTH,
connections without FQDNs in the HELO command are dropped, but that is local
policy. Just as implementing DRIP/RMX/DMP/SPF/Vixie in an MTA is a local
policy decision.

> -----------snip--------------
>     Sometimes a host is not known to the domain name system and
>     communication (and, in particular, communication to report and repair
>     the error) is blocked.  To bypass this barrier a special literal form
>     of the address is allowed as an alternative to a domain name.  For
>     IPv4 addresses, this form uses four small decimal integers separated
>     by dots and enclosed by brackets such as [123.255.37.2], which
>     indicates an (IPv4) Internet Address in sequence-of-octets form.  For
>     IPv6 and other forms of addressing that might eventually be
>     standardized, the form consists of a standardized "tag" that
>     identifies the address syntax, a colon, and the address itself, in a
>     format specified as part of the IPv6 standards [17].
> -----------snip--------------


Raymond S Brand