[Mimedefang] Revisit: Filtering on HELO

Graham Murray gmurray at webwayone.co.uk
Sat Mar 17 06:07:27 EDT 2007

"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."

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