Fix email delivery issues for error code 5.7.23 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 5.7.23 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 fix it? Email admin icon I'm an email admin. How do I fix this?

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

Only an email admin in your Office 365 organization can fix this issue. Contact your email admin and refer them to this information so they can try to resolve the issue for you.

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

This bounce message most likely indicates a Sender policy framework (SPF) configuration issue in your Office 365 organization.

The Diagnostic information for administrators section in the bounce message will contain the original error message when Office 365 tried to send the message to the external email server or service.

To fix this issue, do the following steps:

  • Verify the SPF DNS record for your domain at a publicly available SPF or DNS record checker on the web.

  • Verify that the outbound message wasn't identified as spam by Office 365 and routed through the High Risk Delivery Pool. Messages in the High Risk Delivery Pool won't pass SPF checks, and therefore won't be accepted by the destination email organization.

    To receive Bcc copies of outbound messages that are determined to be spam, see Configure outbound spam policy notifications in Office 365.

    If you determine that the outbound message was incorrectly detected as spam by Office 365, contact support.

Still need help with error code 550 5.7.23?

Get help from the Office 365 community forums

Admins: Sign in and create a service request

Admins: Call Support

See also

Email non-delivery reports in Exchange Online