[Mailman-Users] messages fail to @yahoo @aol @outlook

Mark Sapiro mark at msapiro.net
Sun Jul 28 18:05:14 EDT 2019

On 7/28/19 7:58 AM, Loren Engrav via Mailman-Users wrote:
> Greetings
> I use Mailman (2.1.26) at Site5.com.
> Several of the member addresses are @yahoo.com @aol.com and @outlook.com.
> Messages to these address bounce and fail and / or just fail.  Messages to other addresses pass.
> The latest notice(s) are summarized below.
> Site5 people cannot seem to fix this.  
> Any advice for me / Site5? (I am not expert at this)
> Final-Recipient: rfc822; engravosaurusrex at aol.com <mailto:engravosaurusrex at aol.com>
> Original-Recipient: rfc822;engravosaurusrex at aol.com <mailto:engravosaurusrex at aol.com>
> Action: failed
> Status: 4.4.2
> Diagnostic-Code: X-Postfix; delivery temporarily suspended: lost connection
>    with mx-aol.mail.gm0.yahoodns.net <http://mx-aol.mail.gm0.yahoodns.net/>[] while sending RCPT TO
> Final-Recipient: rfc822; engravosaurus at yahoo.com <mailto:engravosaurus at yahoo.com>
> Original-Recipient: rfc822;engravosaurus at yahoo.com <mailto:engravosaurus at yahoo.com>
> Action: failed
> Status: 4.4.2
> Diagnostic-Code: X-Postfix; delivery temporarily suspended: lost connection
>    with mta5.am0.yahoodns.net <http://mta5.am0.yahoodns.net/>[] while sending RCPT TO

These are 4xx statuses which are retryable so presumably they are
retried until the retry time limit is up and are finally turned into
permanent failures.

The recipient Yahoo MX servers, more than one, are disconnecting after
sending a (presumably OK) response to MAIL FROM. This means there is
something about the sending server that they don't like. There are
different sending servers here as well. They are
gateway1.unifiedlayer.com and gateway13.unifiedlayer.com.

This is not a DMARC issue nor anything that can be fixed with DKIM,
because the receiving server disconnects before it has seen any of the
message. It has seen enough to validate SPF because that only requires
the MAIL FROM domain, but I've never personally seen or heard of servers
disconnecting that suddenly because of an SPF failure, but it's
possible. It's also possible that the sending IPs are blacklisted by
Yahoo (and maybe by Microsoft - Outlook). AOL's MX is Yahoo.

My best guess is Yahoo really doesn't like unifiedlayer.com, but is
waiting for the recipient address before hanging up because it may
accept special addresses like maybe postmaster.

This is something that has to be worked out between unifiedlayer.com and
Yahoo and maybe outlook.com.

Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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