[Mailman-Users] List posts sent to AOL list subscribers bounce as undeliverable (v. 2.1.20)

Mark Sapiro mark at msapiro.net
Fri Dec 4 13:01:14 EST 2015

On 12/04/2015 03:21 AM, Woody Mon via Mailman-Users wrote:
> The issue is that list posts sent to AOL subscriber addresses are now bouncing as undeliverable with the bounce code: "521 5.2.1 :  AOL will not accept delivery of this message."

This is a rather non-specific AOL error message, but as you note, it is
documented. I've seen mail rejected by AOL for this reason, but the only
circumstance under which I've seen it on my own server is when an AOL
user posts to a list (with DMARC munge from in effect) the copy to that
user is rejected with that reason, but it is accepted for other AOL
members of the same list. I've dealt with this by setting all AOL list
members to 'not metoo'. I've never been able to figure out what in the
message causes this.

I see this reject quite often on mail.python.org, but we've seen no
complaints from the python.org lists about this, so I don't think it's
all AOL users all the time.

In the cases I've seen, the only reasons listed for this at
<https://postmaster.aol.com/error-codes#other> that might apply are
"RFC2822 From domain does not match the rDNS of sending server." and "IP
has a poor reputation and mail is sent to multiple recipients.", but if
one of those is the cause, why in the first case above is only the
poster's copy rejected?

> This issue just began several days ago and 200+ subscribers with AOL email addresses are now identified as bouncing in Mailman admin.
> I understand last year AOL (and Yahoo)  made changes to their email systems which might contribute to this issue. However it didn't seem to impact our list subscribers with AOL email addresses until just now.

The changes have to do with DMARC, and if AOL rejects a message for
DMARC policy reasons it normally responds with one of the documented
DMARC codes.

> Unfortunately the list server runs on a host machine maintained by another non-profit, which in turn contacts with a small local hosting provider. And we don't have access to changing any list server configuration parameters, beyond what is available in the list owner admin. 

And I wish I knew what you could change if you could, but I don't.

> And unfortunately the hosting provider will not make any changes to the server for specific lists. We are just grateful the free listserv service and that they keep the version of Mailman up-to-date.
> And we are unable to setup a white list or feedback loop (FBL) with AOL as we don't have access to the postmaster or abuse email accounts for the list server domain.
> We have sent an email to http://postmaster.info.aol.com/SupportRequest.php
> to request unblocking out list email address and/or the list server IP (assuming one or the other is actually "blocked", we have no idea at this point), but have yet to receive a response from AOL.
> The error codes page at https://postmaster.info.aol.com/error-codes
> says this about the bounce error noted above:
>    AOL will not accept delivery of this message
>    This is a permanent bounce due to:
>        * RFC2822 From domain does not match the rDNS of sending server.
>        * RFC 2822 FROM address does not have an A record and is not a valid domain.
>        * IP has a poor reputation and mail is sent to multiple recipients.
>        * There are multiple From address in the mail headers and the IP reputation is poor.

The first reason above is really bad. It's looks like AOL's own
extension to DMARC that ignores any DMARC policy that might actually be
published by the From: domain. On the other hand, I don't expect AOL to
properly document what they are doing anyway. You could try setting
from_is_list on your list's General Options page to Munge From or Wrap
Message. If that solves the problem, then it is that first reason, but I
suspect it is more likely the third and the answer is to improve your
IP's reputation with AOL, but you may not be able to do that.

> Before I dive into the details above and the info within the document at https://postmaster.info.aol.com/tech-requirements, I'm hoping to hear some potential simple solutions that may be applied to our particular solution. 

I'm not aware of any.

> I can post the content of the list email a headers, but I wish to avoid posting the info in a public forum,

I don't think that will be helpful. You do need to look at them and
determine that the Mailman sending server at least meets the following:

Identifies itself in HELO/EHLO with a host name whose A record matches
its IP address.

Its IP address has a rDNS (PTR) record pointing back to the same host

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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