Version 2 (modified by Enrique Rosas, 8 years ago) (diff)


En otros idiomas:

DMARC and Mailing Lists

In early April, Yahoo changed their email policies (and called this change an aggressive level of DMARC) in an effort to stop spam and phishing against it's users. This policy change requires Yahoo users to change the way they use their email services and has caused widespread problems with users throughout the Internet, including May First/People Link Members.

As a side effect, they are pressuring their users (and users of other email providers) to avoid using third party email list services.

If counter measures are not taken, messages sent from Yahoo email addresses to our email lists will bounce when delivered to many providers, including but not limited to Gmail and Comcast accounts. Once enough bounces are recorded, subscribers from the those accounts will be removed from your lists.

What should you do?

  • If you are sending messages to our email lists from a Yahoo account, please stop immediately.
  • If you are a May First/People Link member, please open a support ticket to ask for help in setting up a May First/People Link email address ( in case you are not using one already.
  • Change your email provider, to one that does not enforces aggressive levels of DMARC, or even better, join May First/People Link as member.
  • Either way: stop using Yahoo to send messages to your email lists.
  • If you manage an email list configured for discussion, please email your list warning them about this problem and asking that subscribers with Yahoo addresses stop sending messages to the list.

To help mitigate this problem, May First/People Link is modifying messages sent to our email list servers from Yahoo email addresses - we are re-writing the From address to be from a email account rather than the original yahoo address. As a result, you may see messages posted to your email list with a From address like:

"Jose Garcia <>" <>

If you reply to this email message, the reply will go to: and the user will get an auto-response referring them to this page.

Technical Details

Yahoo has published information to all mail providers telling them to reject any message that claims to be from Yahoo that does not properly prove it was sent from a Yahoo server. When you send a message to an email list, the email list will resend that message to all subscribers to that list. As a result, the message is not being sent from a Yahoo server, it is being sent from the server running the mailing list. When evaluating reception of email, destination servers are not able to verify that the message was originated from Yahoo, so they reject the message.

For more information, please see: