An Update On Yahoo’s DMARC Policy Warren Duff April 11, 2014 Best Practices, Technical // SUMMARIES ?> A recent change in Yahoo’s DMARC validation policy may be preventing your messages from being delivered. Recently, Yahoo made a significant change in their Domain-based Message Authentication, Reporting, and Conformance (DMARC) policy. DMARC is a system for implementing Domain Keys Identified Mail (DKIM) and Sender Policy Framework (SPF) validation and authentication. With a DMARC policy in place, if an email address does not match the domain server/service it originated from, it is bounced or blocked. This is a great security measure for preventing emails from companies spoofing mail domains from reaching the inbox. Yahoo has introduced a DMARC record that tells receiving email servers to reject “from “addresses with the yahoo.com domain being used if they don’t originate from their servers. This is a great thing for preventing email spoofing, but it can potentially raise some problems for smaller senders. An Example: Let’s say you’re a company that sends email from a yahoo.com address: email@example.com. In order to reach your mailing list subscribers, you send a message to your mailing list where another server distributes your message to the individual list subscribers. For your subscribers who have email accounts with providers that check DMARC (like Gmail or Outlook), the message will now be blocked and they won’t see it. This is because the message your subscriber receives comes from the mailing list server, and not the Yahoo server associated with your email address (firstname.lastname@example.org). What Does This Mean For You? As a SendGrid customer, if you’re sending mail to subscribers from a yahoo.com address through our servers, your messages will be blocked by any email client checking DMARC. Don’t worry! SendGrid has a way for you to correct this! The easiest way to correct the Yahoo DMARC change is to change your email address. Rather than use a yahoo.com email address, you should change the email you send from to a non-yahoo.com address. SendGrid strongly suggests sending mail from your own domain that you control. If you still want to keep your yahoo.com address, you can then set the Reply-To field to keep it. To learn more about the Yahoo DMARC change, and what bounce messages you need to watch out for so that you know if you’re being affected by this change, visit our Knowledge Base article Yahoo DMARC Changes / “Message not accepted for policy reasons.“ As always, if you need any assistance with your account, please feel free to contact one of the email experts at SendGrid Support!