First, let him email whoever he wants, but make sure he knows something about the school. The coaches wont take him seriously if all he writes is " I want to play lacrosse" Tell him to get a little information, then he can email away. there is no harm going big. Just have him look at other programs as well.
This is good advice - if you (may) want business, for example, say something like "I am planning on major in business and I am very interested in your XYZ school of business.
Doesnt sound like much, but coaches read all of these to build their data bases (read: solicit for prospect days where they earn $$). Differentiation helps