Hello there hartmuth1. We have read your message. We try to help you.

https://support.mozilla.org/en-US/kb/cannot-delete-messages

If you are using IMAP, a new Trash folder will be automatically created by Thunderbird. Trash.msf

You cannot delete trash as before? I will search for you in our database from Thunderbird.

If you can make a startup in safe modus and check the functions again please to find out if this trashcan is the issue or not.

https://support.mozilla.org/en-US/kb/safe-mode-thunderbird Choose for disable all ad-onss.

Greetings Firefox volunteer.

Thanks, I tried both suggestions, but I can´t delete messages as before. But: I can create a new folder and paste messages from the input folder to that new folder. In that new folder I cannot delete the single messages but I can delete the whole new folder. It then appears in the trashbox, unable to delete it from there. What is there behind? And the problem remains when I re-install Thunderbird! Very strange.

Hello there again

Your trashcan cannot delete the folders.oké. Dragging it to the trashcan it s oke. Are those files still in the folder that s in the trashcan as you mentioned it?

Check your system for double trashcan icons. Maybe you had a update where other existing folders or maps where you had put a Exe file from Thunderbird. Forgotten and still there. Look for all double icons on your system that could be a problem.

You can try to

Go into account setting then in server setting set the option to place deleted messages in to the trash folder. Once that is set the folder will have the special attribute that causes Thunderbird to treat it as a trash folder and show the trash icon.

Try to restore trashcan .See link please. https://support.mozilla.org/gl/questions/1242802

Greetings Firefox volunteer.