If possible, delete your data folder: c:\users\"you.user"\appdata\local\thunderbird (Windows Vista or superior) or/and c:\users\"you.user"\appdata\Roaming\thunderbird (Windows Vista or superior) ~/.thunderbird (linux) *this delete all your data. **make a backup before. ----- ''Moderator Note: Deleting [https://support.mozilla.org/en-US/kb/profiles-tb user profile data] '''is never''' recommended as it will cause data loss. If you want to test in a clean profile, you can [https://support.mozilla.org/en-US/kb/using-multiple-profiles create a new profile] using the profile manager while keeping the old profile folder on your system. If necessary, you can move important data to the new profile. [http://kb.mozillazine.org/Profile_folder_-_Thunderbird Mozillazine] has an explanation of these important files to transfer. '' This particular issue, however, is a bug in Thunderbird 32 and should be fixed in the upcoming release. There is no need to touch profile folders here.

https://support.mozilla.org/en-US/questions/1018230

If you follow the experts you'll see that this turns out to be a bug in v32, to be fixed in the next release. Thanks to those who responded with info on the upcoming bug fix