nocal baseball is right. Our experience was that serious interest involved lots of phone calls (with the once a week limit for D1s), emails, a call from the college to the high school coach, sometimes a request for a videotape and then an invitation to visit, followed by more phone calls if the player hasn't made a commitment to the program after the visit.
I think that it can be pretty exhausting for a kid to get his hopes up every time one phone call, or one form letter, is received. Most of these go nowhere.
I think that as a parent, you have to be supportive, and make sure that your son follows through and answers inquiries, but also be careful not to make things even harder for your son by making evaluative comments (or screams) when something is received from a baseball program. By acting that way, you will get his hopes up, and most of the time, they will be dashed. That can be really exhausting and confusing for a kid.