When you create a proof you have the option to add a 'custom mesage'. Is this visible anywhere after the Proof has been created?
The only place I've been able to see it is if I go into the Proof admin area, open the proof there, scroll down to messages, click the tiny 'I' icon, then the message is visible in the body of the email. It would be better if this message was visible in Updates or somewhere more accessible by regular users. I beleive this view is only available to admins.