I received this message below within SendGrid that was being sent to Gmail. However this has always worked, and of course I am have a FROM email address included. Is this something else or a bug?
550 5.7.1 [220.127.116.11 11] Our system has detected that this message is not RFC 5322 compliant: 'From' header is missing. To reduce the amount of spam sent to Gmail, this message has been blocked. Please visit https://support.google.com/mail/?p=RfcMessageNonCompliant and review RFC 5322 specifications for more information. k7si5926825iok.8 - gsmtp