Oops..2nd time, sorry - had to resub to NANOG and hadn't actually
sent the sub to -post.
Except possibly don't use the word "spam", or anything else that is
liable to trip SpamAssassin and friends into giving your messages a
high score (so references to abdominal anatomy and cable tv decoders
are also probably unwise :).I'm frequently surprised that more people don't run their (legitimate,
opt-in, whatever) bulk mail through SpamAssassin before they send it
in order to see how spam-like it looks. I'm forever having to pick
itineraries and electronic tickets from airlines out of my spam
folder.
Send them to us; we're happy to tell them to use Habeas. 
(SpamAssassin is a partner, and whitelists mail using our
headers, so those itineraries and e-tickets will sail through SpamAssassin, along
with about 3 dozen other ISP and spam filter partners Of course, if it's
mailing list mail, it *has* to be confirmed opt-in.]
Anne