Stephen Farrell wrote: > Please just answer "keep", "modify", or "remove" in this thread, and > use a different subject line for any discussion.
(Using a different subject line as requested.) My conclusions from reading ssp-03 and the proposed rewording of section 4.3 found in levine-adsp-00 and otis-adsp-02 is that: * ssp-03 and levine-adsp-00 require that you check that the domain exists. otis-adsp-02 makes it an optional test. * checking NXDOMAIN is not a perfect check for the test "is this domain a MAIL SYSTEM", but can be considered a "sufficient" check for the purposes of ADSP. * levine-adsp-00 provides a superset of methods for *how* to determine if the domain exists: the NXDOMAIN test and the "check MX & A/AAAA" method from SMTP. It leaves it up to the implementation to choose the algorithm that works best for it. * otis-adsp-02 only specifies the "check MX & A/AAAA" method from SMTP, but indicates that an NXDOMAIN return value breaks out of the first part of the test. * as implied by otis-adsp-02, checking NXDOMAIN can be treated as an optimization for one of the failure paths of the "check MX & A/AAAA" method. (If you check for the MX records and get NXDOMAIN, you know you don't need to explicitly check for A/AAAA records because you've already been told that they don't exist.) * from discussions on the list, not all implementations may be able to take advantage of that optimization. Weighing the above, I find the text in levine-adsp-00 as the most palatable wording for this test. Hence my "modify" vote. Tony Hansen [EMAIL PROTECTED] _______________________________________________ NOTE WELL: This list operates according to http://mipassoc.org/dkim/ietf-list-rules.html