FWIW, the L_RCVD_TOO_MANY_HOPS rule will hit on *a lot* of corporate mail. Off the top of my head I can think of at least two dozen large companies that this would hit. I wouldn't be surprised if it hit more ham than spam.
Heck, forget corp mail, what about sourceforge.net mailing lists? SF adds 3 hops just by itself.
