Email alert for offending email senders
There is a brilliant tool well placed in the Email Section:
Home » Email » Mail Delivery Reports
This is a good place to find offending accounts in troubleshooting email-reputation problems.
It would be great to have a daily email alert to server admin if a user exceeds x % failed+deferred so we can take active preventive measures in time, not only after the fact and repair the faulty accounts/scripts.