[Mailman-Users] AOL rejecting connections from mailman servers for DMARC Munging.

Robert Heller heller at deepsoft.com
Wed Aug 24 14:02:00 EDT 2016

At Wed, 24 Aug 2016 10:32:06 -0700 Mark Sapiro <mark at msapiro.net> wrote:

> On 08/23/2016 03:55 PM, Ted Hatfield wrote:
> > 
> > Few mails from IP xxx.xxx.xxx.xx were getting rejected from one of
> > filters as Reply-to address is same as the TO address. This is caused as
> > one of our filters triggered these emails as spam. I have added
> > protection for your IP. As a good mailing practice, please use a
> > different email address for your reply-to address.
> Don't munge Reply-To: ;)
> > It seems to me that since dmarc munging adds the senders address to the
> > reply-to header, if a user receives a copy of their own postings this is
> > the result.
> No. Based on AOL's reply above, this has nothing to do with DMARC. If
> you set reply_goes_to_list to This list (note that Poster is the
> /strongly/ recommended setting) both the To: and Reply-To: headers of
> outgoing messages will contain the list address.

And if reply_goes_to_list is set to Poster and the poster sent to himself and
CC's to the list, the To: and Reply-To: headers the outgoing message will
contain the poster's address :-(. (This legal, but generally is going to
require interesting finagling by the E-Mail client.) Note that this assumes
that AOL really means the To: header. It *could* mean the union of the To: and
Cc: headers. Eg if the address in the From: is also in the To: OR Cc: headers,
AOL might reject the E-Mail. (This would be seriously dumb and effectively
make AOL an impossible E-Mail destination to deliver any E-Mail to.)

It does relate to DMARC, in that in order for a Mailman list to allow Yahoo, 
et. al. users to post, you have to have Mailman munge the From: field and then 
to allow "reply to sender", Mailman needs to be configured to put the poster's 
address in a Reply-To: header.

> However, it seems that this means AOL will not accept mail from any list
> with reply_goes_to_list = This list, and since this is a common,
> although not recommended, configuration, if this is the case, it seems
> there should be much more reports of this issue, and I haven't seen that.
> > Can anyone else confirm that this has happened to them and if so what
> > else can someone do except to wrap the message from senders that
> > implement dmarc rejection as in dmarc_moderation_action?
> Even if this is a DMARC issue, Wrap message won't change it because the
> headers in the wrapper will be the same as those in a Munge from message.
> > Is there a recommended policy regarding this issue?
> Set reply_goes_to_list to Poster



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