Most get removed now, but there must be some lingering from over the years. May have to make it a sliding scale where the fee doubles each time they send profane messages complaining that it is my duty to clean up after them. Apparently they confuse me with someone that gives a rip about the problem they created.
The amazing part is that even as we get letters asking us to clean up after old spam there are people trying to create new spam of the same nature. Maybe if they'd read webmaster forums instead of spam them they'd know they're screwing up.