Thunderbird is a computer program that runs on your device. It is not a web site and nothing is processed anywhere but on your local machine. Now given that you are the only one that can see what is going on because everything happens on your local machine. Perhaps you might drop a bread crumb or two to those you are asking for help. Perhaps share the error message you are seeing and describe what you are trying to do. Do you have an antivirus product installed? DO you have the same issues with it disabled? Do you use a VPN? Does the outcome change if you turn it off?