Microsoft 365 Exchange Error Code 5.7.1 – Delivery not authorized

In this post, let’s have a look at the error message “5.7.1 – Delivery not authorized” 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.

Error Message

5.7.1 – Delivery not authorized

Error Details

The sender of the message isn’t allowed to send messages to the recipient.

This error occurs when the sender tries to send a message to a recipient but the sender isn’t authorized to do this. This frequently occurs when a sender tries to send messages to a distribution group that has been configured to accept messages only from members of that distribution group or other authorized senders. The sender must request permission to send messages to the recipient.

This error can also occur if an Exchange transport rule rejects a message because the message matched conditions that are configured on the transport rule.

For more information, see Fix email delivery issues for error code 5.7.1 in Exchange Online.