Someone correct me if i'm wrong, but even if the player leaves a voice mail, the coach can't call the player back before july 1, period. I coach at a juco and don't know all of the d1 recruiting rules, but i'm pretty sure that only the player can contact the coach. If that's the case, an intro letter really won't be that helpful right now. i'd wait and send one in january with a copy of your schedule and a list of a few other guys on your team that is of d1 caliber. the higher the amount of quality players that the coach can see at one time will help him choose to come watch your game vs. another. you just need to make sure you stand out when the coach comes.
Also, what has deterred me from taking a player was the expectations that i had of the player, due to a letter from the player, or a phone call from his summer or h.s. coach. If a pitcher will hit 90mph in a game twice, and truthfully sits at 86-88, don't include in your letter that you throw 90mph. In that situation, when I get to the game and see that pitcher throwing 86-87, I leave a little disappointed. Even if he hits 90 a couple of times. If the player had told me that he threw 88mph, and was consistently 86-88, while hitting 90 a few times, I would leave thrilled with the amount of "upside" this guy has.
Not sure if this is how every coach is, but I, personally, would always want the absolute truth about the abilities that a player has.
With that, I would recommend asking a coach, rather than the player, to write a letter on your behalf. I promise it will be taken more seriously than a letter coming from johnie or daddie.
I'm not trying to dissuade any player from expressing interest in a program to their coach, but leave it at that. Don't include personal achievements cause the college guys will take it with a grain of salt, no matter how truthful it is. But never over sell yourself, it will just make you look bad in the long run. The praises, the stats, the attributes are all great, but the bottom line is, can you play, or can you not.
www.blastbat.com