How can I speed up Spam Assassin?
If you have any addresses your get lots of mail from you
can "whitelist" them. This means that Spam Assassin won't
check any mail from that address.
In file /etc/mail/spamassassin/local.cf add:
There is some danger in to doing this. A spammer might lie and
say their mail address is one of these. So don't add your entire
address book. Only add trusted high-volume addresses.
For more info: