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Applies to Product -Dynamics 365 Lifecycle Services


What’s happening?
Customers are experiencing mail authentication failures when attempting to set up SMTP for sending emails. The error message indicates that mail authentication has failed, prompting users to verify their SMTP username and password.


Reason:
The underlying cause of this is related to the configuration of SMTP settings, including the use of legacy authentication methods that are no longer supported by Microsoft. Additionally, there may be issues with the security settings in the Azure portal that prevent successful SMTP authentication.


Resolution:
To resolve the SMTP mail authentication error, follow these steps:

  1. Verify SMTP Settings:
  2. Go to System administration > Setup > Email > Email parameters.
  3. Open the SMTP settings tab.
  4. Ensure all fields are populated correctly, including the SMTP server (e.g., smtp.office365.com), port (587), and that SSL/TLS is enabled.
  5. Check Authentication:
  6. Ensure that the Authentication required option is checked.
  7. Re-enter the SMTP username and password to avoid any cached data.
  8. Verify the password and username by trying to log in on Outlook Web App with the same credentials.
  9. Reset the password if unsure of the typed one.
  10. Check Security Defaults:
  11. If your organization has security defaults enabled, it might prevent sending emails through SMTP client authentication.
  12. Disable the Azure Security Defaults by toggling the Enable Security Defaults button to No in the Azure portal under Microsoft Entra ID > Properties > Manage security defaults.
  13. Test Email:
  14. Open the Test email tab in the Email parameters form.
  15. Enter a valid Send to address value.
  16. Click Send test email to verify if the configuration works.
If the error persists after following these steps, further investigation may be required to ensure that the SMTP settings and user permissions are correctly configured.