Manuel,
I just sent you an email to your address on MSN and the answer was:
This is the Postfix program at host xxx.yyy.tld.
I'm sorry to have to inform you that your message could not be be delivered to one or more recipients. It's attached below.
For further assistance, please send mail to <postmaster>
If you do so, please include this problem report. You can delete your own text from the attached returned message.
The Postfix program
<your_mailbox_at_hotmail_manuel@hotmail.com>: host mx1.hotmail.com[64.4.50.99] said: 550 Requested action not taken: mailbox unavailable (in reply to RCPT TO command)
Can you empty your mailbox at hotmail?
-Nuno