Possible answers:
[1]. He probably has more than one email address, a civilian one and a military one. He may also have a mailing address and a phone number you could use.
[2]. Ask him if he has a cell phone in case of emergency. Make sure that you leave the batteries in his phone safely so that you don't accidentally remove them from his pocket later.
[3]. Find out his email address and phone number and note any missions or others you will need to invite him to on. You may have to describe your priorities for this person in your head.
[4]. Instead of emailing your boyfriend, send him a personal email. Be sure to also do come by his house and are in his public surroundings.Choose from options above and answer: What most naturally follows?

How to be a navy girlfriend
Ask about how to contact him.
Your sailor may have many ways in which you can contact him or he may only have a few. Know the different methods to talk with your boyfriend and which one you should use for what situation.
Answer:
[1].