Nowdays browsers should do the validation that provides immediate feedback to the users (using <input type=email ...>), so the article rightly claims that just sending an e-mail should be sufficient for the server side code. Most of the stuff that passes the browser's input filtering will be nonexistant rather than malformed addresses.

OTOH, most languages have proven, stable libraries for validating e-mail addresses (e.g. Mail::RFC822::Address for Perl).