Hello! All the messages in the sent folder have been lost. When I use webmail, all the messages appear normally. I sent a test message from Thunderbird 151.0 (64-bit) / Windows 10 (64-bit) and the message does not appear anywhere in Thunderbird, but I can see it in "webmail". I added the same email account to TB on another PC and I have the same problem. I have deleted this specific email account from TB and reinstalled it, but the problem persists. In Outlook (iPad and PC) it works normally. Other email addresses of the same domain work normally everywhere. The email server provider cannot help me and claims that there is a technical problem on my side. Is there anyone who has any idea on how to solve this particular problem? Thank you.