Fix email delivery issues for error code 5.7.57 in Exchange Online

It's frustrating when you get an error after sending an email message. This topic describes what you can do if you see error code 550 5.7.57 in a non-delivery report (also known as an NDR, bounce message, delivery status notification, or DSN).

Email user icon I got this bounce message. How do I fix it? Email admin icon I'm an email admin. How can I fix this?

Why did I get this bounce message?

When you connect to the endpoint to submit (relay) messages through Microsoft 365 or Office 365, you need to authenticate with the credentials of a user who has an Exchange Online mailbox. This bounce message indicates a problem in the configuration of the connecting application or device.

I got this bounce message. How do I fix it?

I'm an email admin. How do I fix this?

The distinction between an end user and an admin is blurred for this bounce message, as the problem lies within the configuration of the application or device.

Still need help with error code 550 5.7.57?

Get help from the community forums

Admins: Sign in and create a service request

Admins: Call Support

See also

Email non-delivery reports in Exchange Online