SMTP Code: 550-5.7.26 unauthenticated email from example.com is not accepted...

Products

• Messaging Gateway

Issue/Introduction

When attempting to deliver email to Gmail or a Google hosted mail server, the message is rejected with the following response:

550-5.7.26 unauthenticated email from example.com is not accepted due to domain's
550-5.7.26 dmarc policy. please contact the administrator of example.com domain
550-5.7.26 if this was a legitimate mail. please visit
550-5.7.26  https://support.google.com/mail/answer/2451690 to learn about the
550 5.7.26 dmarc initiative. - gsmtp

Environment

Component: DMARC

Cause

Message delivery is failing DMARC authentication. 

Resolution

• Confirm that Messaging Gateway is configured to sign outbound messages using DKIM.
  • Protocols > Domains > domain > Delivery > DomainKeys Identified Mail.
• Confirm that that DKIM records are published to the DNS and are correct.
• Confirm that SPF records are published to the DNS are and correct.

Additional Information

• Wikipedia: DomainKeys Identified Mail