If your account is IMAP then you most likely experience the folder corruption problem described in this bug. https://bugzilla.mozilla.org/show_bug.cgi?id=1890230

Try to repair the affected folder(s).

sorry but this forum is terribly unreadable to the casual user i would ask more for instructions with clear steps :) the other thing is that with this tool https://www.emailadepts.com/pl/ThunderbirdRecovery.htm can i repair these damaged directories mbox if it is about them?

To repair a folder, right-click the folder in the folder pane - Properties - Repair Folder

Which folder to fix? Can you provide the path?

Hello there

Do you choose the folder that is suspected of containing the problem specified to us?

Greetings Firefox volunteer

Hello there We have read the question We try to help

If you want to repair the folder, choose the folder to repair, if you want to rearrange multiple folders and also repair it, this is a second process called erasing the msf files.

Greetings Firefox volunteer

Hello there

Make sure that the software is not running Thunderbird.On your computer itself, search your PC's hard drive for the Mozilla Thunderbird folder profile folder. IMAP accounts for the IMAP and pop accounts for the locale folder.look for the inbox.msf folder in which you contain your mail also the mbox.msf can.erase the inbox.msf files here.erase only the msf files not the rest without them.(Msf)

After that, try to restart your thunderbird program, this will bunk the designated erased items and put them back automatically.if you want to repair a single folder, do this with your mouse and with the folders of thunderbird if it is enabled, you will suffer from a bug and the whole thing will not disappear as it should. Then you can still delete and reinstall your account with your own login details.

Greetings Firefox volunteer

folder repair helped thank you and best regards

When your problem is fixed, can you mark the topic as 'Solved' please? Thank you.