Yesai, Could you, please provide with a screenshot? Do you believe your problem is similar to this one? https://support.mozilla.org/en-US/questions/1317528?

Right-click the folder in the Folder Pane, Properties, Repair Folder, to rebuild the folder index.

Yesai, Could you, please provide with a screenshot? Do you believe your problem is similar to this one? https://support.mozilla.org/en-US/questions/1317528?

Yes its the same issue, but i don't want to repair my folders every two days we must have e permanent solution of this issue as we know that the cause is Thunderbird updates versions and way that Thunderbird saves the mails if you are developer of Thunderbird register this issue as a bug and solve this issue like check mbox file while starting the Thunderbird or change the way of saving messages