Ciao, ok l'errore l'ho trovato, ma adesso mi dà quest'errore:
Warning: require_once(C:\xampp\htdocs\agenda\agenda-mod\class.smtp.php): failed to open stream: No such file or directory in C:\xampp\htdocs\agenda\agenda-mod\phpmailer\class.phpmailer.php on line 968
Fatal error: require_once(): Failed opening required 'class.smtp.php' (include_path='.;C:\xampp\php\PEAR') in C:\xampp\htdocs\agenda\agenda-mod\phpmailer\class.phpmailer.php on line 968