Ecco ho provato a fare cosi e funziona

Codice PHP:
<?php 
$currentDate 
date("d.m.Y - H:i:s");
$ip $_SERVER['REMOTE_ADDR'];

if (isset(
$_POST['Submit']) && $_GET['action'] = "insert") {
mysql_select_db($database_name$conn) or die (mysql_error());
$query "INSERT INTO tb_guesbook (gb_callsign, gb_name, gb_linkName, gb_linkUrl, gb_dateTime, gb_object, gb_text, gb_email, gb_ip) VALUES (
                                                                                '"
.mysql_real_escape_string ($_POST['callsign'],$conn)."',
                                                                                '"
.mysql_real_escape_string ($_POST['name'],$conn)."',
                                                                                '"
.mysql_real_escape_string ($_POST['linkname'],$conn)."',
                                                                                '"
.mysql_real_escape_string ($_POST['linkurl'],$conn)."',
                                                                                '"
.mysql_real_escape_string ($_POST['dateTime'],$conn)."',
                                                                                '"
.mysql_real_escape_string ($_POST['object'],$conn)."',
                                                                                '"
.mysql_real_escape_string ($_POST['text'],$conn)."',
                                                                                '"
.mysql_real_escape_string ($_POST['email'],$conn)."',
                                                                                '"
.mysql_real_escape_string ($_POST['ip'],$conn)."'
                                                                                                )"
;
mysql_query($query) or die (mysql_error());
$msg "Messaggio inserito con successo!
Message insert successfully!"
;
}
                                                                                                

?>

Pero quel malefico di un utente riesce ancora mettere messaggi alla cazzo ;
Altri consigli per evitare il tutto??

Date un'occhiata qui