Extract any valid emails from a string

gistfile1.aw

<?php

/**
 * Extract any valid emails from a string
 *
 * @param string $str 
 * @return array matched email addresses
 */
function extractEmails($str)
{   
    $str = strtolower($str);

    preg_match_all("/([a-z0-9+_]|\\-|\\.)+@(([a-z0-9_]|\\-)+\\.)+[a-z]{2,6}/", $str, $vals);

    $email_a = array_map(function($email) {
        // Perform a more thorough validation
        if (false === filter_var($email, FILTER_VALIDATE_EMAIL)) {
            return false;
        } else {
            return strtolower($email);
        }
    }, $vals[0]);

    $email_a = array_unique($email_a);

    return $email_a;
}