Subject: [apps-discuss] Comments on draft-martin-smtp-target-host-selection-ipv4-ipv6-01

From: Jason Fesler <[email-masked]>
Date: Thu, 30 Jan 2014 15:18:30 -0800

As I re-read http://tools.ietf.org/html/rfc5321#section-5 ..

   When the lookup succeeds, the mapping can result in a list of
   alternative delivery addresses rather than a single address, because
   of multiple MX records, multihoming, or both.  To provide reliable
   mail transmission, the SMTP client MUST be able to try (and retry)
   each of the relevant addresses in this list in order, until a
   delivery attempt succeeds.  However, there MAY also be a configurable
   limit on the number of alternate addresses that can be tried.  In any
   case, the SMTP client SHOULD try at least two addresses.

I wonder if Mr. Martin's draft should be simplified; to simply amend
5321 by modifying the last line:

   In any case, the SMTP client SHOULD try at least two addresses of
each address family found.

That would seem to address most issues except perhaps the caching of
unreachable destinations.

-- 
 Jason Fesler, email/jabber <[email-masked]> resume: http://jfesler.com
 "Give a man fire, and he'll be warm for a day;
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