Email Validation Function

email-valid.php

<?php
/**
 * emailValid
 * Email Validation Function
 * I take an email as a string and test it against 2 regular expressions.
 *
 * @author Regexp Author unknown
 * @author Phillip Harrington <philsown@gmail.com>
 * @param string $email
 * @return bool $valid
 */
function emailValid($email)
{
    $valid = false;
    $email = trim($email);

    if (0 < strlen($email)
        && !preg_match('/(@.*@)|(\.\.)|(@\.)|(\.@)|(^\.)/i', $email)
        && preg_match('/^.+\@(\[?)[-a-zA-Z0-9\.]+\.([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$/i', $email)
    ) {
        $valid = true;
    }

    return $valid;
}

I used to have the strlen block and the 2 preg if blocks each separately return false throughout, but lately I'm in a single point of exit mindset.

I cannot take credit for the regexps - I borrowed them from someone who borrowed them. If the real author is known, please comment and attribute.

I did however make one edit, which was to increase the TLD portion from 3 chars max to 4 - to account for .info email addresses. One character - my big contribution!

Enjoy!