SPAMMERS can be very creative. They know that posts will be shut down quickly, so every once in a while they will resort to using the mail / message systems.
As Ron stated if anyone receives any message that is unwanted - SPAM or otherwise - please forward that message along with your comments to any moderator or the site Administrator.
Just in case you're not familiar with the moderator names:
Dutch, Monty, Ron50, PigCicles. TulsaJeff is the forum owner / administrator.
As soon as someone receives the message they will promptly take care of the problem.