Private Message Setup - Receive, but not send

[induslady]

I am trying to make private message a paid feature in my site. Obviously, paid members can send and receive private messages. However, I want to set-up such that even non-paid members can "receive" private messages, but can't respond. That way the paying folks can send private message to everyone in the forum, not just the paying minority. Is there a way to set that up? Thank you for your help.