
Quoting
aardvarc
Harassing communications charges in all states generally require multiple communications over a period of time. IF this is a single email sent from one adult to another, police aren't likely to give a hoot unless there is some form of threat involved. Beyond the police however, he could be looking at anything from academic suspension to explusion if she reports it to the school. Most schools have very explicit rules about sending such emails to or from a school-based email address, especially to another student (check the school's sexual harassment policy).
What advice can you give? Tell him to quit drinking if he's going to do stupid things like this that could ruin his academic career - and then tell him that he can consult with a criminal defense attorney if he is in fear of law enforcement action or if she files for a restraining order (but from where I sit, his biggest worry at this point should be what the school could do if she tells).