Good information Nina!
We have our children's phone accounts limited to only 10 people that they can call and text to AND from. So I couldn't figure out how they kept receiving ad type text messages from unapproved accounts. Obviously it is from their e-mail accounts. I never thought about this before.
The whole reason we downgraded (in our kids opinions, we as parents considered it upgrading) to the limited accounts was because my 16 yr old son received sexually threatening text messages last year. We actually wound up getting the police involved in it. He was sent nude pictures, too. But honestly I was not disturbed by the pictures nearly as much as the things that were said. "I will rape you, faggot" - and things like that. It was truly disturbing.