Falling back to A when there is an MX (especially after receiving any kind of SMTP response from the MX) is an RFC violation by the way (rfc 5321 section 5.1) Even then - this doesn't appear to be the case. The bounce below was generated entirely within Hotmail. From SNT133-WS53 (a hotmail webserver) to snt-omc3-s27.snt0.hotmail.com - which I believe is part of their outbound mail farm. That's where the bounce was generated. "Requires authentication" might be because whatever domain is being sent to was originally hosted on hotmail, and set to require authentication to relay out through hotmail's servers. --srs On Tuesday, October 23, 2012, Michiel Klaver wrote:
Carlos,
check the mail logs of your web-server, your domain might have a primary A-record pointing to something different than MX-records. When the MX servers do something like greylisting and bounce with a temp-code (4xx) hotmail servers will try alternative records (like @ IN A) and might find a listening mail-daemon at your webserver.
At 23-10-2012 00:16, Carlos M. Perez wrote:
Hi,
We're trying to resolve some delivery issues reported by hotmail users. Started happening a few weeks ago. Getting immediate NDRs, and the server that is supposed to receive the email has no records of attempts. The messages also don't match what the receiving server should be sending. The server(s) listed in the MX should receive all email without authentication, since it's a mail filtering service (Maxmail)
= Reporting-MTA: dns;snt0-omc3-s27.snt0.hotmail.com Received-From-MTA: dns;SNT133-W53 Arrival-Date: Mon, 22 Oct 2012 14:09:49 -0700
Final-Recipient: rfc822;administrator@xxxx.com <javascript:;> Action: failed Status: 5.5.0 Diagnostic-Code: smtp;550 authentication required =
Kindly contact me off-list.
Thanks,
-- --srs (iPad)