What-is-DMARC?Enter DMARC–Domain-based Message Authentication, Reporting & Conformance. DMARC was created to tell a participating receiving server what to do with a message that fails both SPF and DKIM validation. In other words, what to do if a message claims to be from you, but isn’t. DMARC standardizes how email receivers perform email authentication using the well-known SPF and DKIM mechanisms. This means that senders will experience consistent authentication results for their messages at AOL, Gmail, Hotmail, Yahoo! and any other email receiver implementing DMARC
How am I affected?
If you utilize a form on your website which has visitors send an email using a 'FROM' field in which they input their email addresses, there is a chance that the email will fail due to authentication if DMARC is being used by the @domain.com address. As of this writing, this only affects @yahoo.com addresses, however this may change in the future.
Note: Emails which are rejected due to the DMARC policy will normally indicate as much within the error itself. An example of an email rejected by Gmail can be seen below:
** firstname.lastname@example.org F=<email@example.com> R=lookuphost T=remote_smtp: SMTP error from remote mail server after end of data: host gmail-smtp-in.l.google.com [126.96.36.199]: 550-5.7.1 Unauthenticated email from yahoo.com is not accepted due to domain's\n550-5.7.1 DMARC policy. Please contact administrator of yahoo.com domain if\n550-5.7.1 this was a legitimate mail. Please visit\n550-5.7.1 http://support.google.com/mail/answer/2451690 to learn about DMARC\n550 5.7.1 initiative. sd1si21689276obb.46 - gsmtp
What can I do to fix this?
We recommend that you update the 'FROM' field within your form to use an email address of @yourdomain.com. Additionally, the 'REPLY-TO' setting can be used with any DMARC compliant address and will successfully send emails without rejection such as @yahoo.com, @hotmail.com, @gmail.com, or @aol.com.
An example can be seen in the following header:
$headers = 'From: firstname.lastname@example.org' . " " .
'Reply-To: email@example.com' . " " .
'X-Mailer: PHP/' . phpversion();
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