Ciao,
grazie per la risposta..
Ho usato preg_match() e mi da il seguent Warning...
Warning: preg_match(): Empty regular expression in


if (email_is_valid($youremail) && !preg_match("\r",$youremail) && !preg_match("\n",$youremail) && $yourname != "" && $yourmessage != "" && substr(md5($user_answer),5,10) === $answer) {