You haven't said if you first changed your e-mail password with your e-mail provider. Changing the password used in Thunderbird does not change your password with the e-mail provider. It is not a good idea to have the same password for several different purposes. It's even a worse idea to say publicly that you do so! Log into your webmail to make sure you have the correct password. In Thunderbird, '''1.''' From the menu bar, select Tools: Options: Security section: Passwords tab. Or From the menu button, select Options: Options: Security section: Passwords tab. You will see what I show in my first screenshot below. '''2.''' Click the '''Saved Passwords''' button. '''3.''' In the list, find the entries for the e-mail address in question, and remove them. Click Close on this window, then OK on the Options window. '''4.''' Check for new e-mail. The window shown in my second screenshot below will pop up. Type in your password, then check-mark the option "Use Password Manager to remember this password", then click OK. '''5.''' The first time you send an e-mail, it will ask you for your password again.