Everything is stored in your profile folder, which is located in Roaming\Thunderbird, UNLESS you deliberately change settings to save them elsewhere. Who is your email service provider? Some outgoing servers automatically save copies of sent messages in the Sent folder on the mail server.

Hi Stans, thanks for trying to help - I checked my details with my ISP - unfortunately nothing about sent mail.

Using a browser, sign in to your email account and check if they are in the Sent folder.

That's what I have done - I should probably expressed myself more clearly, however nothing was there.

Open your profile folder, go to the Mail > {pop server name} subfolder. Check if there is a file named "Sent".

Hi Stans, there were lots of strange things going on with my PC. Last time I installed TB there was no folder created either in programs or programs (86) - just a TB.exe on C: - I found out this morning after I had a good sleep. I then decided to uninstall TB on C:\ again and start afresh. TB came up with a little box asking for approval. I almost fell into a trap, because when I took a closer look it emerged that most of the data to be deleted was part of a backup file on a separate HD. NO idea how that could happen. I disconnected the Backup and did the TB-uninstall then. After that I copied the TB folder from Users....(extracted from the backup) to the empty User... Installed TB and surprise: ALL GOOD  :))

Thanks for your attempts to help me.

I hope that my description of fixing the problem will help other users.

Cheers, Joe

Thunderbird does not install at the root of drive C: Always download Thunderbird from the official website, thunderbird.net. I have no idea what the little box asking for approval is. Also, the regular Thunderbird installer/uninstaller does not delete any data. It only removes Thunderbird's program files. It doesn't even touch its own data folder ( Roaming\Thunderbird), so whatever it is you were seeing is definitely not coming from Thunderbird's normal installer/uninstaller. Something else is sure going on on your PC and you need to have it looked into. That crash that caused Thunderbird to disappear is highly curious. Thunderbird does not get erased from your PC when TB itself crashes. Sounds to me like your PC is malfunctioning and anything could be the cause, including malware and hardware failure.

Hi Stans, you stated that TB "does not install at the root of drive C:". Until today that was my understanding as well, however I took a pic so I can prove it. Similar "the regular Thunderbird installer/uninstaller does not delete any data". I can prove that it happened. "Thunderbird does not get erased from your PC when TB itself crashes." That's what I and my son, who has been working as a programmer for >20 years, thought as well. We spent many hours trying to hunt down what was going on. BTW, I haven't had a virus for more than 20 years.

What's your explanation for the TB uninstaller trying to delete TB-data from a separate HD with a system backup?

Everything ATM is still working FINE. Cheers, Joe

Hi Stans, you stated that TB "does not install at the root of drive C:". Until today that was my understanding as well, however I took a pic so I can prove it.

Let's see it.

Similar "the regular Thunderbird installer/uninstaller does not delete any data". I can prove that it happened.

Please do.

What's your explanation for the TB uninstaller trying to delete TB-data from a separate HD with a system backup?

This is a first for me. I'd have to see what proof you've got to even begin to understand what was going on.