What is the most correct way to validate an e-mail address?

PHP makes it pretty easy:<p><pre><code> if (filter_var($email, FILTER_VALIDATE_EMAIL)) { $emailvalid = 1; }</code></pre>

I used one of those "close" regexes last time I needed to do this in C#. I believe I went with<p><pre><code> ^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.(?:[A-Z]{2,4}|museum)$</code></pre>

Do not roll your own. Use a library. You will miss stuff.