Cease and Desist message from local police re: foreclosure help mailer

[Clayton P.]

Hey all

Got a voicemail from the local police, saying You need to stop right away the "help with foreclosure" messages (yellow letter'd pre-foreclosures with auction dates in the next month or two) yadda yadda.. I heard there was some kind of legal aspect to this kind of marketing but I didn't pay attention, I'm just learning by doing and pursuing all routes.

I'm not worried at all about this by the way, but does anybody want to fill me in on how it's illegal to mail preforeclosures saying I can help them avoid the situation?

So the question is, are there any other marketing niches that can get the cops called on me?