I haven't responded to any of theses thankfully *knock on wood* but I have a provider friend that did and she spent weeks dealing with email and cell phone spam (she included her phone number in the response).
I always scroll down when I receive an email because I've seen ones that look really legit until you scroll down a little and there are a bunch of random letters across the bottom. Scam.
It's annoying the lengths people go to just to get your information. Someone sits around all day responding to ads (or setting up bots that do it automatically) just to get your information