Karma

karma - reward nice and penalize naughty mail senders

Karma records the number of nice, naughty, and total connections from mail
senders. After sending a naughty message, if a sender has more naughty than
nice connections, they are penalized for I<penalty_days>. Connections
from senders in the penalty box are tersely disconnected.

Karma provides other plugins with a karma value they can use to be more
lenient, strict, or skip processing entirely.