Can the clients be set-up to post the first message? Currently, when my clients log into a new job, there is not a message tab until I create the first message. Is there a way they can post the first message?

+1 for this. We have to add a step into our process just so they can post us a message.

How about writing a standard welcome message that you post on all new projects?

as a matter of process I always post the first message with the project request email. I use this to prove that the project was requested and that it has legitimate value. We do this to keep control of the projects, we have over 70.