[MlMt] I see AOL has joined Yahoo in setting their DMARC policy to 'reject'

[Brad Knowles]

On Apr 23, 2014, at 10:31 AM, Kee Hinckley <kee+freron at hinckley.com> wrote:

> For list owners, this basically means that either:
> 
> 	• Your mailing list makes no changes to the body of the message in any way and passes through the DMARC headers. (I think this works, leastwise I’ve heard on the NANOG lists that posting to NANOG from Yahoo works if you do text-only (they discard the HTML).

Nope.  We're fighting this on the Mailman installation for python.org.  If you make no changes, then the IP address of the MTA for the mailing list won't match the advertised list for the sending domain, and therefore that message will be rejected.

> 	• Your mailing list sets the From: header to a local address (e.g. no-reply at yourdomain) and puts the user’s address in the Reply-To.

Correct.  We are releasing Mailman 2.1.18 to allow listowners to address this issue, but you can also fix it in the MTA before the message gets to the mailing list.

A couple of my fellow postmasters for python.org are also well-known postfix developers (Patrick and Ralf literally wrote "The Book of Postfix"), and one of them is in the process of creating a milter on behalf of the DMARC committee that would allow people to easily fix this problem at the MTA.  I would expect to see an announcement via the DMARC committee on this subject in the near future.

> Needless to say, if you’re used to sorting mail by user, deleting mail based on the from address, or other common operations in MailMate, you’re in for a rude surprise if the mailing list does #2.

Yup.

> I’m mentioning this here mainly because I suspect it’s may mean subtle changes in how MUAs handle lists.

Yup.

--
Brad Knowles <brad at shub-internet.org>
LinkedIn Profile: <http://tinyurl.com/y8kpxu>