Delivery status notifications (DSN) generated using the Messaging Gateway (SMG) content filtering action "Send delivery status notification" are rejected by Office 365 and outlook.com as violating RFC 5322. DSNs generated by normail mail operations such as bounces and out of office responses are unaffected.
550 5.7.512 Access denied, message must be RFC 5322 section 3.6.2 compliant and include a valid From address
This is a known issue with Office 365 / outlook.com's strict interpretation of RFC 5322. Delivery status notifications are delivered using the SMTP special sender "<>" which has no return email address / mailbox unless one is specified in the Reply-To header. Traditionally, the string "MAILER-DAEMON" has been used as the display sender in the From header to indicate to the recipient that the message is service generated:
Since the display sender does not contain a valid sender email address, Office365 / outlook.com is rejecting the message as violating RFC rather than distinguish between standard email messages and service generated delivery status notifications.
This is a known issue and will be addressed in a future release. Please subscribe to this article to be automatically notified of any updates.
As a workaround, a notification template similar to the following can be created to mimic a delivery status notification via Content->Notifications and the action set to "Send Notification".