Updated Thunderbird today. Sending the first message after the seemingly successful install resulted with an error stating it could not save the file to the sent folder, save manually. I clicked save got a message the file was saved, though I did not save the location (sorry). I sent another message and it never saved that sent file or even complaint about it. I did send Bcc and got the mail but no sent file entry. Please advise if this is a bug and if you are working on it. Rolf D Ebert