Unfortunately even if someone did agree to receive these things, and then makes a spam complaint when they receive them, swearing they didn’t sign up, you usually get put on a spam list, then you have to spend lots of time getting your domain off it. Such a pain in the ass.
I actually wish people would take note of where they put their email addresses… it would make it easier for the guys who genuinely got the email from a double opt in.
Thats the next point, get them to double opt in to the newsletter. Better to be safe than sorry.