Good Day! I have to email accounts running thru Thunderbird, one is IMAP and running fine, the other is a POP3 account and over the last week it has been receiving mail but not allowing outgoing mail. I got it to work a couple of time by clearing start-up cache, but that no longer works either. I have shut the program down, I have restarted the computer and still no luck. The error message simply comes up with a yellow triangle and says "Sending of the message failed". Any help would be appreciated. Kurt von Rice