There is no clearer way for a man to declare to the world that he is a spineless, hen-pecked little worm than to have only one email address -- which he shares with his wife.
You can't carry on a correspondence with him, which is probably no great loss to you. More to the point, he can't really carry on a correspondence with anyone else.
It's as if he's saying, "I have no secrets worth keeping, no opinions which any female would find offensive, no independence, no life of my own."
"I've been neutered and I have no problem with that."
Suit yourself, buddy.