One popular technique is to put something in the message that looks like non-spam. I think run-on sentences are supposedly good or something.
Like
“Roberta pulled out her broom and mop, thinking that it was time for a cleaning; it had been many days since the leaves had been swept from the doorstep, and there was quite an accumulation of material that had been gathering over the past six or seven days.”
(I was originally going to post something far more . . . exciting. But . . . exciting stuff often triggers spam filters).