Dealing with DMARC for Mail intermediaries

I’ve been getting some mail and calls from folks looking for help on resolving the issue of DMARC bouncing. Some of these calls are from ESPs, but others are from SAAS providers who have users that have signed up with yahoo.com addresses and are now dealing with mail from those users bouncing, even when mail is going back too those users.
None of the solutions are really great, but here are a couple options.
1) Prohibit users users from sending with @yahoo.com header-from addresses. This will be challenging for some companies for all sorts of reasons. I have seen a number of people suggest switching to @hotmail.com or @gmail.com addresses. This only works as long as Gmail and Hotmail/Outlook don’t start publishing p=reject policies. It’s unclear if they’re even considering this at all, but it may happen.
2) Rewrite the header-from address from @yahoo.com to something you control. One thing I’ve been suggesting to customers is set up a specific domain for rewriting, like @yahoo.ESP.com. This domain would need to forward mail back to the @yahoo.com users, which does add another layer of complexity as these addresses will become spam magnets. Thus the forwarding IP should be on a distinct and separate IP, to prevent interference with other systems. Note, too, that any users sending to these reply addresses from a domain protected by DMARC p=reject will bounce.
If you have questions or want to ask specifically about what to do in your setup, I’ve blocked out some time in my schedule next week for companies. If you want more information about this please contact me to for available times, information requirements and pricing.

Yahoo DMARC articles worth reading
Yahoo Statement on DMARC policy

Related Posts

Open relays

Spamhaus wrote about the return of open relays yesterday. What they’re seeing today matches what I see: there is fairly consistent abuse of open relays to send spam. As spam problems go it’s not as serious as compromised machines or abuse-tolerant ESPs / ISPs/ freemail providers – either in terms of volume or user inbox experience – but it’s definitely part of the problem.
I’m not sure how much of a new problem it is, though.
Spammers scan the ‘net for mailservers and attempt to relay email through them back to email addresses they control. Any mail that’s delivered is a sign of an open relay. They typically put the IP address of the mailserver they connected to in the subject line of the email, making it easy for them to mechanically extract a list of open relays.
We run some honeypots that will accept and log any transaction, which looks just like an open relay to spammers other than not actually relaying any email. They let us see what’s going on. Here’s a fairly typical recent relay attempt:

Read More

Example bounces due to Yahoo p=reject

There are a number of different bounces that people are reporting due to Yahoo publishing a DMARC record of p=reject. I decided to put some of those bounces here so confused users could find out what they needed to do.
Comcast

Read More

Problems with Yahoo FBL

There are a couple problems I’ve been alerted to with the Yahoo FBL today.
The first comes from Michael Ellis and is about broken FBL reporting at Yahoo.

Read More