[Mailman-Users] DMARC and Bellsouth, etc.

Tom Lieuallen toml at engr.orst.edu
Wed Apr 16 22:30:02 CEST 2014


Thank you very much for the summary of solutions.  I was about to 
suggest/request it.  It may be helpful to add to the wiki as it seems 
quite important and complicated. I'd be interested in more mails like 
this, helping those of us move forward and alleviate the issues.

Unless I'm overlooking something, there is another option that appears 
to work.  The anonymous_list option repackages the mail enough that 
gmail no longer marks it as spam.

I don't think it's appropriate for most lists, but could be mentioned as 
another option.  Unless it's similar to option 2 below. I'm not familiar 

Lindsay Haisley also suggested:

"What I'm advising list admins here, which puts a band-aid on the
problem, is to put all yahoo.com subscribers on moderation, effectively
making them read-only subscriptions.  Also go through your membership
list and clear any nomail disablements with a "[B]" beside them."

Is there any way to make these changes with a script, or would one have 
to do it manually?

I'm also curious if the spam options (header_filter_rules or 
bounce_matching_headers) might be options to catch inbound messages from 

Thank you all

Tom Lieuallen

On 4/16/14, 11:11 AM, Stephen J. Turnbull wrote:
> Jose I. Rojas  writes:
>   > 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.
> What it means right now is that posts with "@yahoo.com" in the "From"
> header field will not be delivered to users whose subscribed addresses
> are at a long list of large email service providers.
> If emails posted by users with "@gmail.com" and "@harvard.edu" etc
> addresses are getting through to everybody, but emails from
> "@yahoo.com" members are not, then the problem may very well be
> Yahoo!'s DMARC policy.
>   > Our ISP tells us domain is "RFC-compliant" and problem must be with
>   > Bellsouth or Yahoo.
> That's not very helpful of them.
>   > How do we resolve this?  What is the fix?
> If in fact the problem is Yahoo!'s DMARC policy, you can't resolve it
> and there is no fix.  Simply put, Yahoo! does not permit their users
> to post to modern mailing lists that conform to the mail standards.
> There are four possible workarounds, depending on the access you have
> to your mailing list's configuration:
> (1) You can tell your members with @yahoo.com addresses to post from a
>      different domain.  This is what I personally recommend, as it (a)
>      conforms to Yahoo's stated policy and (b) makes Yahoo users
>      unhappy with their provider, whose behavior is causing denial of
>      service to thousands, perhaps millions, of mailing list users.
>      My experience with this approach is "no complaints", but my users
>      are unusual in that they don't really care about their yahoo.com
>      addresses for various reasons.  People who do most or all of their
>      mail using Yahoo addresses will find this painful.  Depending on
>      how actively you want to protest Yahoo's behavior, you may or may
>      not be willing to impose that pain.
> (2) You can break your mailing lists by using the author_is_list
>      option in Mailman 2.1.16 and later.  This option will only be
>      available if the site configuration has ALLOW_AUTHOR_IS_LIST set
>      to "Yes".  This will cause the list to replace the author's
>      address with its own address in "From".  However, your domain may
>      not permit this, as it's a clear violation of the mail RFCs.
> (3) There is a patch to have Mailman encapsulate posts from yahoo.com
>      addresses in a "one-message digest".  This is RFC-conformant, but
>      some users may have difficulty reading such mail.  (Frequently
>      reported on iPhones.)  It also requires using a third-party patch
>      for Mailman, which may be prohibited by your ISP or beyond your
>      technical capability in the short run.
> (4) You can operate Mailman in pure pass-through mode.  I believe it
>      is sufficient to configure Mailman to (a) have a completely empty
>      header (not even whitespace) (b) a completely empty footer (c) no
>      list prefix in the Subject header field.  This is conformant to
>      the RFCs, but may place you in violation of anti-spam law (because
>      for most users there will be no visible indication of how to
>      unsubscribe from the list).

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