[Mimedefang] Revisit: Filtering on HELO

Philip Prindeville philipp_subx at redfish-solutions.com
Sat Mar 17 14:53:53 EDT 2007

Graham Murray wrote:
> "Kevin A. McGrail" <kmcgrail at pccc.com> writes:
>> SHOULD means in RFC-speak that it should do what is said unless you
>> understand the ramifications of not following the recommendation.  In
>> short, I see nothing in the RFC that could argue that sending just the
>> hostname is proper.  It's either the FQDN or the address literal.
> And an earlier section (2.3.5) actually has a MUST NOT covering this.
>    "The domain name, as described in this document and in [22], is the
>    entire, fully-qualified name (often referred to as an "FQDN").  A
>    domain name that is not in FQDN form is no more than a local alias.
>    Local aliases MUST NOT appear in any SMTP transaction."

That would mean then that an unroutable address like
[] is also a "local alias", and hence forbidden.


More information about the MIMEDefang mailing list