This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
Warning to others: my computer's security system won't allow me to connect to the link in the original post, saying it's a "security risk".
As for validating an e-mail address, I recommend that you don't do that. If the users want to give you their e-mail addresses, you don't need to validate them. They are going to give you a correct and well-formed address. Just send a confirmation e-mail to whatever the user gives you to confirm that you do indeed have the correct address.