Your boyfriend will probably get in trouble. He needs to turn it in IMMEDIATELY. If possible you could call his command and warn them before the letter gets there.
Depends on what he does with it when he opens it.
he's gonna have a LOT of 'splainin to do Lucy. he will DEFINITELY Get into trouble. possibly enough to get him kicked out.
OK I am pretty sure that your BF wont get in trouble for this .. but I cant say what may happen to his friend.. weed is illegal.. but as long as your bf tests negative for drugs I think all will be fine for him I do think though that your boyfriend should ask his friend not to write him again until he finishes boot camp :)