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Re: MX to CNAME and (mis)interpretation of 2821

2008-02-25 03:15:34

John C Klensin wrote:
The tentative text in 2821bis-08 now reads as follows

# When a domain name associated with an MX RR is looked up and
# the associated data field obtained, the data field of that
# response MUST contain a domain-name.  That domain-name, when

How about changing the latter line with the following?

#   response MUST contain a host name. That host name, when

Section 2.3.4, "Host", defines exactly that. I think "host name" is a better term because the hyphenated "domain-name" may induce causal readers to search for a corresponding ABNF or other definition in vain.

# queried, MUST return at least one address record (e.g., A or
# AAAA RR) that gives the IP address of the SMTP server to
# which the message should be directed.  Any other response,
# specifically including a value that will return a CNAME
# record when queried, lies outside the scope of this
# standard.  Such responses could, in principle, be covered by
# an SMTP extension in the future.

+1 for removing the latter sentence.

#                                   The prohibition on labels
# in the data that resolve to CNAMEs is discussed in more
# detail in RFC 2181, Section 10.3 [29].

BTW, is it correct to cite "RFC974" (three times in 2821bis-07) even if it has been obsoleted? I don't know if the tag "obsoletes: 974" that is present in rfc2821 would also be obsoleted by rfc2821bis so that rfc974 would eventually return to a non-obsolete status.