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

God Bless You....I'm On Yahoo.com email...Please help me. Ism this possible for email to be blank...on and off...Or Maybe they are just saying that. For an excuse.