Before setup, please try to login WebMail once, just to make sure your email address and password are correct!
If error message was shown, please try to read it, or send it to us.
If connection failed, but it ask for password, it means your password is wrong. (use copy-and-paste, do not type)
If connection failed, but it does not ask for password, it means it is a connection problem, please try the other connection method (SSL/STARTTLS/No-SSL, etc)