vthrottle is an implementation of an SMTP
throttling engine for Sendmail servers, based upon
M. Williamson's 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". vthrottle tells the misbehaving client
to hold on to the deferred mail and resend it at a
later time.
