TB hangs looking up IMAP server

Suggest you try starting up Thunderbird in offline mode. Either Start Thunderbird as normal Immediately look bottom left of Status bar and click on the go 'Offline' icon located bottom left if you hover over the icon it has a tooltip 'You are currently online' - click on that icon to go offline. OR Use the Profile Manager You can choose the 'Work Offline' option and then click on 'Start Thunderbird' and it will start up in offline mode. Info here: https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-thunderbird-profiles#w_start-the-profile-manager-when-thunderbird-is-closed I created a permanent shortcut icon on desktop just to open 'Profile Manager' so if needed it's much quicker to run. Create a normal shortcut to Thunderbird. Right click on Shortcut and select 'Properties' Edit the 'Target' So if Target says: "C:\Program Files\Mozilla Thunderbird\thunderbird.exe" Add a space then a dash then a capital P So Target says: "C:\Program Files\Mozilla Thunderbird\thunderbird.exe" -P click on 'Apply' and click 'OK' Yes, those '''"''' really exist in the Target and it's not me adding it. Then I renamed it as 'Thunderbird Profile Manager' This this get you access to Thunderbird so can remove the account ? After removing the account - also remove the stored passwords associated with that account. Then you can go back to online mode and enter the account again or not as the case may be. Bottom left of Status bar - click on the offline icon to go to an online icon. If this information worked for you please mark this comment as the Chosen Solution.