SpamPD is a program used within an e-mail delivery system to scan messages
for possible Unsolicited Commercial E-mail (UCE, aka spam) content.
It uses an excellent program called SpamAssassin (SA) to do the actual
message scanning. SpamPD acts as a transparent SMTP/LMTP proxy between
two mail servers, and during the transaction it passes the mail through
SA. If SA decides the mail could be spam, then SpamPD will ask SA to add
some headers and a report to the message indicating it's spam and why.

Homepage:
https://github.com/mpaperno/spampd/
