Error code 550 5.7.x in Microsoft Exchange

Issue symptoms

End users receive a bounce back notification from Microsoft after they send an email to a support address.

The notification starts with: Your message could not be delivered.

The message includes an error or status code with 550 5.7.x.

The emails don't reach Zendesk.

The text of the message will be different for each underlying issue. However, the main problem remains the same: the user's email was rejected before it could reach Zendesk.

Resolution steps

These errors are generated by Microsoft, not Zendesk. Zendesk cannot assist in resolving these errors. If your users suddenly report bounce back notifications and error messages, contact your email administrator. They will need to review the error message and your email configuration.

Note: This type of error can occur on a support address that had been working previously. That typically means something has changed. For example, if Microsoft implements a new policy for email forwarding, existing addresses may not meet the new requirements without an update.

The email administrator for your email domain can investigate and resolve these errors. Microsoft may have updated its policies around automatic email forwarding, and it may affect support addresses that have been working smoothly for a long time. For more information, see this article: Forwarding incoming email from your existing email address to Zendesk Support.