Actually I tried your
[email protected] and it does not work neither via PHP nor Thunderbird. So, either the password is wrong or hotmail.it accounts cannot send messages via SMTP.
I suspect that when you tried sending messages via Thunderbird, you are not setting it to send via smtp.live.com but rather some other SMTP server.
BTW, I discovered your hotmail.it account because you posted the part of the SMTP dialog that contains the user and password encoded in base64. If that is your real account, I suggest that you change the password now.