Hi Guys,
Spamming issues are always a headache for a system admin. Here is a good news for Virtualmin admin, the new version - 4.04 have this new feature to limit mail sending. You just need to login to the panel and specify the values and that's it! This will limit which messages will be accepted by the system, either for local delivery or relaying. This can be useful to prevent spammers from using a hijacked account or website to rapidly send large amounts of email.