Thunder-bird is an E-mail Client- receives mail from your pop3 mailbox sends mail through your SMTP account.
Hotmail[if you mean Hot-Mail ] is a Web mail account operates through the Web side of an ISP
2 entirely different things.
Think about you is not working for you and post again.
If you go to your ISP web site and check your account you should be able to log in[user name then password] and see your mail without- using an E-mail client