ALWAYS email the RC.....NEVER the HC. D3 is the only exception as some programs do not have RC's . If one sends email to a HC at a NCAA D1 program or any other reputable program it is a waste of time. They do not look at it. If the HC has time ( They don't ) he may forward your email to his RC...maybe.
Also, there are serious NCAA recruiting rules with regards to contact w/Sophomores....... You might wanna read up on that. That is also partially why, at least at big National programs, a HC does not recruit. His exposure is too high w/ potential NCAA violations.
College baseball has a clear cut internal chain of command. Not only do HC's not look at recruit email they rarely speak to recruits! At least as far as serious recruiting discussions. They are generally cordial but they only REALLY talk to recruits in the end. You only see the HC when they offer...maybe. Some programs save him till the end. To close the deal. Like Mariano Rivera
As far as email in general , you wanna make sure it's direct to the point and short.They do not talk about players the way we do. A right handed pitcher is a RHP and with Pitchers and hitters they want BODY SIZE ( Height / Weight) and GPA
Your opening paragraph should be something like this. Just the facts:
"My name is John Smith I'm a starting Varsity RHP at Wilson HS . I'm 6'0 170 I throw 3 pitches my FB tops 87 my CB 69 and my CH 79 . I have a 3.8 GPA and will be studying for the SAT soon"
If you son is hitter note bat Left throw Right or whatever he is. List any accomplishments in paragraph 2: "I did area code try-outs last summer, made All-League and did team USA trials"
Paragraph 3: " I'm really interested in playing for UNLV after graduation. Please notify me of any upcoming camps on campus and I'm looking forward to playing in front of you soon"
If your son hasn't done much outside of HS that is fine but my advice is to keep this stuff short and to the point.
Emails at this stage are advertisements for your sons name. Its name recognition only. The idea is to start a dialog ( With the RC not the HC )
It's a process. With several stages. And if your son is talented it is a roller coaster ride. And don't forget , The HC is the grand poobah and needs to handled accordingly. Don't email him
Any of the above is just based on my on personal experience. There are plenty of guys here who have been through this stuff and have their own take on it. Soak up their advice!
Best of luck on your journey