---------- Forwarded message ----------
Date: 10 April 2014 20:05
Subject: Yahoo's Blunder Impacts Mailing Lists Worldwide

Dear Client:

Yahoo initiated a terrible policy change to their mail servers recently that impacts every single mailing list software in use, not just Mailman. If any Yahoo.com user posts to your list, they will cause those list members whose ISP/ESP provider is using DMARC (Hotmail, Gmail, Bellsouth, etc) to bounce the poster's message which can in turn cause the list to remove these members from the list for excessive bounces. The problem is with Yahoo. You can read more about it at:

http://www.pcworld.com/article/2141120/yahoo-email-antispoofing-policy-breaks-mailing-lists.html

https://wordtothewise.com/2014/04/brief-dmarc-primer/

We recommend the following:

1. Resubscribing those list members that were recently removed.

2. Prevent any Yahoo.com subscriber from posting to your list until they subscribe with another non-Yahoo email address. There is no telling when Yahoo will fix this or if they ever will.

Again this issue only affect those lists where Yahoo.com users are allowed to post to the list.