Email Notification of Messages Posted by a Particular User?

Is it possible to set up a member somehow so whenever they post I get an email message notification?

I believe if you subscribe to a thread you will get email updates.

Thanks mojo. That works if they post in the same thread, but alas, it does not work if they start a new thread. I'm trying to find a way to get notified if a particular provider posts a new thread about their travel plans.