I cannot create a new folder in the inbox (or anywhere else)
Why can't this question be answered? You are in a circular denial!
Why can't this question be answered? You are in a circular denial!
Alla svar (1)
Firefox doesn't do email, it's a web browser.
If you are using Firefox to access your mail, you are using "web-mail". You need to seek support from your service provider or a forum for that service.
If your problem is with Mozilla Thunderbird, see this forum for support.
http://www.mozillamessaging.com/en-US/support/
or this one
http://forums.mozillazine.org/viewforum.php?f=39