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; }