What's happening?
The unsubscribe link is not appearing or functioning correctly in email templates. When attempting to access the unsubscribe link, users encounter a 404 error.
Reason:
The unsubscribe link does not function correctly when using the "Test send" feature because the subscription center needs to recognize the recipient to display existing contact information and subscription lists. This functionality is only available in live emails sent from a live customer journey
Resolution:
Do not use the "Test send" feature to verify the unsubscribe link, as the unsubscribe link will not function correctly in test sends. Instead, use a segment to send the email and verify the unsubscribe link functionality.
Enable the "One click-Unsubscribe" feature to ensure proper functionality of the unsubscribe link. For more information on One-click unsubscribe, see One-click unsubscribe support for emails | Microsoft Learn.