IS there a way to ENSURE that when you close Thunderbird down that the authentication session with your email service IS ALSO CLOSED OUT?

I have been seeing this same question for year with similar faulty logic. It I think comes from leaving a web page logged in and the cookies that hold it open in the browser so the best site you access can use them to access your mail. FOlk appear to think mail is a web site and it is not.

Certainly there is an authentication process, there may even be one every few minutes, because the process is connect, check for new mail and end the session. Connect send the mail end the session. Getting mail occurs on a default frequency of every 15 minutes, but I have seen folk setting is as frequently as a couple of minutes others have it set to thirty minutes.

Then there is the "modern" complication of calendars and contacts synchronization et. al. which has it's own authentication protocols and methods.

Can you be sure that Thunderbird is not connected to a session when you click the close button. Not really. But one of two things will occur. The active task will sent an exit command and will close the session, or in some instances the shutdown will be delayed while the task completes. If you crash out like just pull the plug from the wall or force close using the task manager, then the server will time you out in a couple of minutes. Exactly how long is something that is set on the server by the server administrator, but it is rarely longer than 2 minutes. This is where antivirus programs complicate things because the often cause timeouts by being slow in acting so sessions end early.

You probably do not like this answer any better than the others you have found. There are myriad variable that affect the situation. It is not clear cut or simple. Despite the question being so.

Again, this is NOT true. IF this were the case, you would have to input your password every time the system wanted to connect to send or receive e-mail (unless you have your computer remember it, which I do not allow mine to do. This is also how I got my account hacked--by NOT logging out of my email account on my home PC before I deployed over-seas. My Daughter let a friend use the PC and they found my open session (about a year after I deployed) and hacked the email account. MOST email servers (yes I know the difference between an Email Server and a Website and a sharepoint (I'm an admin)) have a menu selection where you can view open sessions. Those sessions will stay open forever unless you manually close them--or the server crashes. Let's see if we can find someone who actually knows if there is a setting somewhere in the menu section of Thunderbird to allow you to manually logout of the server--or if the program (app) is set to auto-log if it is shut down. THIS is the answer I am looking for.