[155116] in North American Network Operators' Group
Re: Is Hotmail in the habit of ignoring MX records?
daemon@ATHENA.MIT.EDU (Ryan Rawdon)
Thu Jul 26 10:11:07 2012
From: Ryan Rawdon <ryan@u13.net>
In-Reply-To: <CAArzuosW4uDsEoP6y087yrdiR32AyqE_2H-DAf-GycbB_6CfrQ@mail.gmail.com>
Date: Thu, 26 Jul 2012 09:10:15 -0500
To: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Jul 26, 2012, at 2:21 AM, Suresh Ramasubramanian wrote:
> If the MX records are not responsive / timing out, they might be falling
> back to the A record.
>
Per RFC2821 (and later RFC5321):
If one or more MX RRs are found for a given name, SMTP systems MUST
NOT utilize any address RRs associated with that name unless they are
located using the MX RRs; the "implicit MX" rule above applies only
if there are no MX records present. If MX records are present, but
none of them are usable, this situation MUST be reported as an error.
So while it is possible they are doing this, they should not be
Ryan
>
> --
> Suresh Ramasubramanian (ops.lists@gmail.com)
