vthrottle is an implementation of an SMTP throttling engine for Sendmail servers, based upon M. Williamsons mechanisms, as described in his 2003 Usenix Security paper. It allows the administrator to control how much email users and hosts may send, hindering the rapid spread of viruses, worms, and spam. Exceptions can be made using a whitelist mechanism, which can be generated manually or with the included tool vmeasure.
