There are two ways to edit smtp server settings. Right click on mail account in Folder Pane and select 'Settings' Account Settings opens in new tab '''Either:''' (Use this method if you are already certain the account is using the correct SMTP server) * Select mail account name in left pane and then look bottom right. You will the Outgoing Server (SMTP) the account is set up to use. * Click on 'Edit SMTP' button * Small window opens and you change the 'Authentication Method' to 'Normal Password' * click on 'OK' '''OR''' * Scroll to the bottom of Left pane and click on 'Outgoing Server (SMTP)' It will show you a list of all your outgoing servers. * Select the smtp server which that account is using and click on 'Edit' * Small window opens and you change the 'Authentication Method' to 'Normal Password' * click on 'OK' Why two methods ? The first method assumes you are already using the correct smtp server which just needs a modification. The second method allows you to check all smtp servers are correct before you select which account uses it. Please note: When you 'Edit' an outgoing server smtp - the 'Description' field is purely for your use - I usually enter my email address which is the same as the user name or a unique description , so it is easy to check the mail account is using the correct smtp server - as seen via first method). This is helpful if an account is using the wrong SMTP server and you need to double check settings. I have supplied some images below as an aid. Remember to restart Thunderbird to ensure it is using those settings.