Programmer Humor

Well, and remember: If in doubt, send them an e-mail. You probably want to do that anyways to ensure they have access to that mailbox.

You can try to use a regex as a basic sanity check, so they've not accidentally typed a completely different info into there, but the e-mail standard allows so many wild mail addresses, that your basic sanity check might as well be whether they've typed an @ into there.