AOL publishes a p=reject DMARC record

Yesterday I mentioned that there were reports of a compromise at AOL. While the details are hazy, what has been reported is that people’s address books were stolen. The reports suggest lots of people are getting mail from AOL addresses that they have received mail from in the past, but that mail is coming from non AOL servers. In an apparent effort to address this, AOL announced today they have published a p=reject DMARC record.
I expect this also means that AOL is now checking and listening to DMARC records on the inbound. During the discussions of who was checking DMARC during the Yahoo discussion, AOL was not one of the ISPs respecting DMARC policy statements. I’m not surprised. As more information started coming out about this compromise, I figured that the folks attacking Yahoo had moved on to AOL and that AOL’s response would be similar to Yahoo’s.
My prediction is that the attackers will be trying to get into Outlook.com and Gmail, and when they do, those ISPs will follow suit in publishing p=reject messages. For those of you wondering what DMARC is about, you can check out my DMARC primer.

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A brief DMARC primer

DMARC stands for Domain-based Message Authentication, Reporting and Conformance. What DMARC does is allow domain owners to publish policy statements in DNS telling receiver domains what to do with messages that do not authenticate. In addition, DMARC introduces the concept of “domain alignment.” What this means is that the authentication has to be from the same domain (or a sub-domain) as the address in the header-from: line. The idea behind DMARC is that organizational owners can use SPF and DKIM authentication to authenticate their actual domain in the header-from line. This moves authentication from a important but behind the scenes technology out to an end user visible technology.

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Yahoo Statement on DMARC policy

Yesterday Yahoo posted a statement about their new p=reject policy. Based on this statement I don’t expect Yahoo to be rolling back the policy any time soon. It seems it was incredibly effective at stopping spoofed Yahoo mail.

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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.

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