Check out 20_freemail_domains.cf that is part of SpamAssassin. It contains all the known "freemail" services, so you could work on the assumption that if it's not one of these, it's "private"
-- Cheers Jason Haar Information Security Manager, Trimble Navigation Ltd. Phone: +1 408 481 8171 PGP Fingerprint: 7A2E 0407 C9A6 CAF6 2B9F 8422 C063 5EBB FE1D 66D1
