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Re: Site policy vs. HELO

2005-03-02 12:42:14

** Sometime around 14:29 -0500 03/02/2005, EdLevinson(_at_)ResultsLifeCoaching(_dot_)com said:

The question posed is: Can a site whose policy is not to do EHLO be in compliance with RFC2821? Or does Sect 7.7 provide an exception to 2.2.1?

Yes, except "% sed 's/EHLO/HELO/'" in your statement above (which is probably what you had intended to write).

<PseudoLegalese to try to be precise>
Better to ask, How can a site be in compliance with both sections? Then, according to 2.2.1, they MUST support HELO and according to 7.7 they may decide to "limit the use of the relay function to known or identifiable sources". Elsewhere, Sect. 3.7, RFC 2821, states, "The relay server may accept or reject the task of relaying the mail in the same way it accepts or rejects mail for a local user." That suggests that a server treat a HELO that same way it treats an EHLO, applying its policies using the (obviously limited) information the HELO provides.

The paragraph in Sect 7.7 that precedes the one quoted makes that clear:

   It is a well-established principle that an SMTP server may refuse to
   accept mail for any operational or technical reason that makes sense
   to the site providing the server.  However, cooperation among sites
   and installations makes the Internet possible.  If sites take
   excessive advantage of the right to reject traffic, the ubiquity of
   email availability (one of the strengths of the Internet) will be
   threatened; considerable care should be taken and balance maintained
   if a site decides to be selective about the traffic it will accept
   and process.

I don't mean to be pedantic, but it is arguably still not clear. Based on that graf, a site could accept EHLO under "proper circumstances" (i.e., well-formed EHLO from a non-blocked site, etc.), yet still reject all use of HELO under any circumstances for "operational or technical reasons that make sense to the site providing the server," where, at that site, "care has been taken and balance maintained [in the decision] to be selective about the traffic it will accept and process."

Thus, a site may arguably _not_ treat a HELO the same way it would treat an EHLO.

Vince Sabio                                                  

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