The mod would have to say for sure but I thought I heard that one can not receive messages unless they are a VIP member.  There is no way for the sender to tell, either.

I just can't understand why any provider would not have a VIP membership. I would never want to see a client knowing that they had access to read information about me that I had never seen. A review could be embellished or just plain false. And there are a lot of guys out there who think that because they read it in a review that it's as good as gold. Also TER mail is a great way to verify a client who has reviews. Not to mention all of the potential appointments that might have been lost by not having the ability to check mail.
Just my 2cents, for whatever it's worth..... Amanda ))