/**
     * Checks e-mail address syntax against a regular expression.
     *
     * @param string $email e-mail address.
     * @return boolean e-mailaddress syntactically valid or not.
     * @static
     */
    function validateAddressSyntax($email)
    {
   
    /*
       The local-part of the e-mail address may use any of these ASCII characters:
      
      Uppercase and lowercase English letters (a-z, A-Z)
      Digits 0 to 9
      Characters ! # $ % & ' * + - / = ? ^ _ ` { | } ~
      Character . (dot, period, full stop) provided that it is not the first or last character,
      and provided also that it does not appear two or more times consecutively.
      
      email validation regex codes:
      if (preg_match("/^[-_a-z0-9+]+(\.[-_a-z0-9+]+)*@([0-9a-z][0-9a-z-]*[0-9a-z]\.)+[a-z]{2,4}$/", $email))  //ATK 6.5
      $regexp = "/^[^0-9][A-z0-9_]+([.][A-z0-9_]+)*[@][A-z0-9_]+([.][A-z0-9_]+)*[.][A-z]{2,4}$/";
        if(preg_match("/^[a-zA-Z]\w+(\.\w+)*\@\w+(\.[0-9a-zA-Z]+)*\.[a-zA-Z]{2,4}$/", $_POST["email"]) === 0)
        if (!eregi("^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$", $email)){

        the winner:
        /^([\w\!\#$\%\&\'\*\+\-\/\=\?\^\`{\|\}\~]+\.)*[\w\!\#$\%\&\'\*\+\-\/\=\?\^\`{\|\}\~]+@((((([a-z0-9]{1}[a-z0-9\-]{0,62}[a-z0-9]{1})|[a-z])\.)+[a-z]{2,6})|(\d{1,3}\.){3}\d{1,3}(\:\d{1,5})?)$/i
        http://fightingforalostcause.net/misc/2006/compare-email-regex.php
       
        see dominic's is_email() parser, a bit more involved:
        http://www.dominicsayers.com/isemail/
       
   */
   
      //if (preg_match("/^[-_a-z0-9+]+(\.[-_a-z0-9+]+)*@([0-9a-z][0-9a-z-]*[0-9a-z]\.)+[a-z]{2,4}$/", $email))
      if (preg_match("/^([\w\!\#$\%\&\'\*\+\-\/\=\?\^\`{\|\}\~]+\.)*[\w\!\#$\%\&\'\*\+\-\/\=\?\^\`{\|\}\~]+@((((([a-z0-9]{1}[a-z0-9\-]{0,62}[a-z0-9]{1})|[a-z])\.)+[a-z]{2,6})|(\d{1,3}\.){3}\d{1,3}(\:\d{1,5})?)$/i", $email))
      {
        return true;
      }
      else
      {
        return false;
      }
    }