In this post, let’s have a look at the error message “5.7.512 – Access denied, message must be RFC 5322 section 3.6.2 compliant” that you get when working with Microsoft 365 Exchange Online.
These are the errors that you usually receive when there is a problem in delivering the email message that was sent by you. These errors are generated and sent by Office 365. This is usually alled as DSN which stands for delivery status notification or in simple words bounce messages.
NDR or Non-delivery report is one of the common type of message that you receive which indicates to the user that the email was not delivered.
5.7.512 – Access denied, message must be RFC 5322 section 3.6.2 compliant
Message was sent without a valid “From” email address.
Office 365 only. Each message must contain a valid email address in the “From” header field. Proper formatting of this address includes angle brackets around the email address, for example,