By proper do you mean legal? (It depends where you live, not legal in the US) By proper do you mean not going to get intercepted or break? We need more details. First things first: if it’s summer where you are this is a bad time of year to be mailing boxes of beer.
Sorry I should have clarified not really get intercepted basically a buddy of mine is turning 21 and I wanna send him a couple bottles and I just wanna know how I can if it's possible