Parents... you can go ahead and try that format... I did. The emails are usually valid beginning a short time before they are given their computers.
If you try to email your PC, and it does not bounce back (as a bad email address), then your plebe will have some email from home waiting for him when he DOES get everything working. HAPPY time!
BTW parents, all midshipmen WILL check their physical mailboxes too... Don't neglect to send 'snail mail' as well. It's a real pick-me-up. One Mid I know (2/c) said: "My mailbox is very lonely, and my email is just full of hundreds of KP emails to go through" They WILL get KP email fatigue.