Unnamed

function is_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;
   }