i have used that tutorial. Now i can login squirrelmail but the page http://mydomain.it/squirrelmail/src/webmail.php
it's a blank page!!!
there's an error in the squirrelmail configtest
ERROR: You have enabled any one of magic_quotes_runtime, magic_quotes_gpc or magic_quotes_sybase in your PHP configuration. We recommend all those settings to be off. SquirrelMail may work with them on, but when experiencing stray backslashes in your mail or other strange behaviour, it may be advisable to turn them off.
now i have turned them off but the problem persist.
There aren't errors in the var/log/main.log and in /var/log/apache2/error.log