<?php

    #
    # RFC822 Email Parser
    #
    # By Cal Henderson <cal@iamcal.com>
    # This code is licensed under a Creative Commons Attribution-ShareAlike 2.5 License
    # http://creativecommons.org/licenses/by-sa/2.5/
    #
    # $Revision: 2717 $
    #

    ##################################################################################

    function is_rfc822_valid_email_address($email){

        $qtext = '[^\\x0d\\x22\\x5c\\x80-\\xff]';

        $dtext = '[^\\x0d\\x5b-\\x5d\\x80-\\xff]';

        $atom = '[^\\x00-\\x20\\x22\\x28\\x29\\x2c\\x2e\\x3a-\\x3c'.
            '\\x3e\\x40\\x5b-\\x5d\\x7f-\\xff]+';

        $quoted_pair = '\\x5c[\\x00-\\x7f]';

        $domain_literal = "\\x5b($dtext|$quoted_pair)*\\x5d";

        $quoted_string = "\\x22($qtext|$quoted_pair)*\\x22";

        $domain_ref = $atom;

        $sub_domain = "($domain_ref|$domain_literal)";

        $word = "($atom|$quoted_string)";

        $domain = "$sub_domain(\\x2e$sub_domain)*";

        $local_part = "$word(\\x2e$word)*";

        $addr_spec = "$local_part\\x40$domain";

        return preg_match("!^$addr_spec$!", $email) ? 1 : 0;
    }

    ##################################################################################    
?>