Don't waste time sending a letter or a phone call to the recruit to make this determination.
Call the coach instead. He'll ALWAYS respond to your effort, and he'll tell you whether it's worth trying to pull the player down.
If it IS worth it, he'll say something like "player X is looking to play at a higher level, but I've heard he might consider (your school) as a backup option if that doesn't pan out".
If it's NOT worth it, he'll say something like "don't take this the wrong way, but he doesn't even know who you are - might want to move on".
Basically, if he doesn't tell you that you are a backup option, he can't be pulled down.