Discussion lists & Yahoo issue

So this happened:

and is certainly affecting Yahoo users on my DH hosted discussion list. Any advice for workarounds? The post suggests Mailman 2.1.16 has a way around it but we’re on 2.1.14.

For context, here’s a description of the issue from the IETF discussion list:


In short, the problem is that Yahoo’s mail servers now have a DMARC policy that declares that any message with a “From” header at yahoo.com which wasn’t sent by Yahoo’s servers is invalid and should be discarded. Since mailing lists normally forward messages on while keeping the original sender, this makes anything they forward from a Yahoo user look like junk!

The workaround you’re thinking of that’s available in some newer Mailman versions is to make all messages from the list always show up with the list address as a sender. This is a poor solution, though, as it makes it much more difficult to search through your mail for messages sent to the list by a particular person… ultimately, Yahoo is probably going to need to change their DMARC policy, as the one they’ve got in place right now is simply too strict.

Oh yeah, this: Yahoo breaks every mailing list in the world including the IETF’s


  • Suspend posting permission of all yahoo.com addresses, to limit damage

You can find all subscribers with a yahoo address from the mailman
list admin page:

  1. select “Membership List”
  2. enter “yahoo” in the search box
  3. click “Search”
  • Tell Yahoo users to get a new mail account somewhere else, pronto, if they want to continue using mailing lists

  • If you know people at Yahoo, ask if perhaps this wasn’t such a good idea

(Those tips from from the IETF email.)

We are working on a Mailman upgrade, however. For this and other reasons.

Or just switch your Yahoo users to digest mode, so the mail comes from your domain.

Is there an ETA on the Mailman upgrade?