I just set up Thunderbird with my new hosted email accounts (HostGator) last night. It went very smoothly. Today, I came home and opened Thunderbird, and when connecting to each of those accounts it alerts me that a certificate from (xxxxx).totalcontrol.host couldn't be validated. I'm a newb when it comes to certificates. Don't have a clue what they are. But I decided to disallow the connection because I can't even figure out, using Google, who or what totalcontrol.host is. And yet I see people posting it, or at least overlooking it, on the very few Google results where totalcontrol.host is cited as being the server address for an Apache installation, for example. Can anybody offer me a clue?
Contact Hostgator to find out. Hostgator rented The Planet's servers and The Planet does have a Total Control Server range of servers and probably that is what you got. The thing is that for most times, SSL is not required or not set up for emails. Perhaps, you might have set the 'Security Settings' in Thunderbird to anything other than 'Never'. Failing which, contact Hostgator who would probably be able to set you to the right path.