Why can the firefox browser not access FTP sites?
Sites that provide anonymous FTP access typically require a password that is a valid e-mail address, and firefox instead provides an invalid one. Worse, it gives you no way to set a correct one via the normal Edit -> Preferences menu path. This seems to be a bug! The error message that you see is in a pop-up window that reports The response `mozilla@example.com’ is not valid … Please use your e-mail address as your password. With some care, you can fix the firefox preferences file, either by editing it directly, or by setting it in the GUI, as described later. To edit preferences manually, first, exit from the browser (otherwise, it will just destroy the preference changes that you are about to make). Then find its file named prefs.js with the Unix command find $HOME/.mozilla -name prefs.js.