Check the following points to ensure that your Active Directory user account is part of the correct distribution group:

1. Verify the user’s group membership:
   Make sure that the user is member of the correct distribution group by verifying the user's current group membership.
2. Check the user’s name and account status:
   Verify that the user's name and account status has not been changed recently.
3. Look up the group membership in the Active Directory's GUI:
   Clarify the group membership by looking it up in the Active Directory's GUI.
4. Review the group policy settings:
   Check the group policy settings to ensure that the user has all necessary rights and permissions.
5. Update the Active Directory:
   Verify that the Active Directory is up-to-date and not corrupted.