I have a client who wishes to only allow mail into his inbox that is
explicitly allowed via his white list. Yahoo currently allows you to do
this (which is where they got the idea).
procmail
--
This story shall the good man teach his son; And Crispin Crispian shall ne'er go by, From this day to the ending of the world, But we in it shall be remember'd;
smime.p7s
Description: S/MIME cryptographic signature
