Hi,
I am not able to get this - Email flow monitoring is must for all service provider to know who all using what counts. Relay from the server may damage IP reputation and putting the server in the blacklist.
Since the server can have more than thousand of websites it’s very complicated to monitor it. It better to have feature list other panel having for admin like
Domains wise relay count, auto alert when the count goes above x on hourly or daily limit etc.