Please be advised that the recent spam filter upgrade has changed the behavior of the login screen.
The username is now your e-mail address.
Previously, by using just your username, and not your entire e-mail address, the domain @misn.com would be appended to your username for you. But, this is no longer the case.
And, unfortunately, the behavior of appending a domain has not been completely disabled. If you do not type in your full e-mail address as the username, you might end up with the wrong domain name and because of this, the wrong spam quarantine.
So, remember.
The username is now your e-mail address.