PGP-based whitelist

http://www.w3.org/2004/07/pgp-whitelist.html
"This article describes how to use PGP to filter incoming email with
procmail, so that messages that you receive and have been signed by
somebody you know gets marked in a specific way - with an additional
header. This is particularly useful in combination with spam-fighting
techniques to avoid that legitimate emails be marked wrongly as spam."

Dom
-- 
Dominique Hazaël-Massieux - http://www.w3.org/People/Dom/
W3C/ERCIM
mailto:dom@w3.org