Yahoo DMARC articles worth reading
There are a bunch of them and they’re all worth reading.
I have more to say about DMARC, both in terms of advice for senders and list managers affected by this, and in terms of the broader implications of this policy decision. But those articles are going to take me a little longer to write.
How widespread is the problem? Andrew Barrett publishes numbers, pulled from his employer, related to the number of senders using @yahoo.com addresses in their commercial emails. Short version: a low percentage but a lot of users and emails in raw numbers.
What can mailing list managers do? Right now the two answers seem to be stop Yahoo.com addresses from posting or fix your mailing list software. Al has posted how he patched his software to cope, and linked to a post by OnlineGroups.net about how they patched their software.
A number of people are recommending adding an Original Authentication Results header as recommended in the DMARC.org FAQ. I’m looking for more information about how that would work.
For commercial mailers, there doesn’t seem to be that much to do except to not use @yahoo.com address as your header-From address. Yes, this may affect delivery while you’re switching to the new From address, but right now your mail isn’t going to any mailbox provider that implements DMARC checking.
One other thing that commercial mailers and ESPs should be aware of. Depending on your bounce handling processes, this may cause other addresses to bounce off the list. Once the issue of the header-From address is settled, you can reactivate addresses that bounced off the list due to authentication failures since April 4.