You can register an email address as "jigglypuff666forever" or whatever nonsense you want. The government certainly doesn't give a shit, and as long as your family and friends know that a specific string of numbers and letters means "you" in the address book, why does it matter?

If you're worried about professionalism, I don't really see much difference between "johnqpublic@email.com" and "greenthumbmcgee@email.com" except one tells the world your full name, and the other just gives away that you like gardening. Both are equally G-rated and acceptable, but only one is a security nightmare.