Answer by Francisco Costa for How can I validate an email address using a regular expression?

^[_a-zA-Z0-9-]+(\.[_a-zA-Z0-9-]+)*@[a-zA-Z0-9-]+(\.[a-zA-Z0-9-]+)*\.(([0-9]{1,3})|([a-zA-Z]{2,3})|(aero|coop|info|museum|name))$

This matches 99.99% of email addresses, including some of the newer top-level-domain extensions, such as info, museum, name, etc. It also allows for emails tied directly to IP addresses.