Thunderbird is hanging at checking mail server capabilities.
Using windows 10. Email provider verified problem is not on their end - no problem sending/receiving with email clients on android tablet/iphone. Email provider suggested not to use firefox.
Alle svar (1)
Try with your OS in its Safe Mode to check if firewalls, antivirus etc are impeding progress.
Why would they suggest you stop using Firefox (a web browser) when you report a problem with Thunderbird (an email client)?