If I start thunderbird with the VPN not running, then later start the VPN and try to switch to my Red Hat Inbox, thunderbird will pop up a dialog saying that it could not connect (even though the VPN *is* running at this point). If I then switch to a *different* folder in my Red Hat account, thunderbird will then connect, ask for my password, etc.

I also see the same thing with my non-RH (non-VPN-requiring) account if the network goes down when thunderbird is running, and then comes back up; sometimes Thunderbird will then give me a "could not connect" error on the account *after* the network has come back.

I'm guessing that what's going on is that at some point, thunderbird tries to check for new mail in the background, and hits a network error. Since the error occurred as part of a *background* operation, it doesn't want to annoy me with an error dialog, so instead it just remembers the error for later. Later, I fix the network situation, and then go to do something in thunderbird, at which point it sees that it has an error saved up for that server, and so it shows me the error without checking first that it's still relevant.