[Mailman-Users] DMARC and Bellsouth, etc.

Jose I. Rojas jirojas at bellsouth.net
Wed Apr 16 17:30:52 CEST 2014

We have a community group mail list which we run using Mailman and have lately had a problem getting our emails to members who have Bellsouth and Yahoo email addresses. I've seen the posts about DMARC but am not that tech-savvy to figure out what this means and how to resolve. Some of our members have complained that they are not getting the group's emails. We have written Bellsouth but they claim the domain is not on a blacklist and problem is not on their end. Our ISP tells us domain is "RFC -compliant" and problem must be with Bellsouth or Yahoo. How do we resolve this?  What is the fix? Help, please...

> On Apr 16, 2014, at 10:48 AM, Mark Sapiro <mark at msapiro.net> wrote:
>> On 04/16/2014 06:58 AM, Lindsay Haisley wrote:
>> Has anyone seen issues with Gmail accounts and Yahoo's DMARC policy?
>> I've been working with the list admins of one of FMP's hosted lists and
>> they've seen over 100 addresses unsubscribed from the usual suspects -
>> yahoo.com, att.net, Comcast, etc., but no Gmail accounts and there are
>> 228 of them on the list.
> This is consistent with what I've observed on lists.
>> Nonetheless, the PC World article at
>> http://www.pcworld.com/article/2141120/yahoo-email-antispoofing-policy-breaks-mailing-lists.html
>> lists Gmail as being one of the cooperating email service providers
>> honoring Yahoo's DMARC p=reject policy.
> I've done some testing. If I send a message from my server, but not from
> a list From: a yahoo.com address to a gmail address, it gets rejected with
>> 550-5.7.1 Unauthenticated email from yahoo.com is not accepted due to domain's
>> 550-5.7.1 DMARC policy. Please contact administrator of yahoo.com domain if
>> 550-5.7.1 this was a legitimate mail. Please visit
>> 550-5.7.1  http://support.google.com/mail/answer/2451690 to learn about DMARC
>> 550 5.7.1 initiative. uc7si1048327pbc.131 - gsmtp
> However, if I send the same message to a list which then resends it
> without touching the From: to the same gmail address, gmail accepts it
> and delivers it to my gmail spam folder.
> Thus, it appears that gmail does honor DMARC policy in general, but has
> some kind of mitigation policy to identify (heuristicly? via headers?)
> mail from a list and quarantine it even if the From: domain's policy is
> reject.
> Note it doesn't use the RFC 2369 List- headers because it still
> recognizes a message without them as from a list.
> -- 
> 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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