Explicit steps will be appreciated. I do not understand "the email is dragged & dropped between the TB columns' - what columns? and then right-clicked and 'move-to option. I regularly move messages from IMAP to a folder with never a problem. I am trying to figure why dragging and right-clicking. It seems that right-clicking would suffice. My hope is that there may be a simple change in what you're doing will fix this. Thank you.

Hello David, Many thanks for your quick reply. Your question regarding 'columns'. When reading my emails I am looking at two 'columns': the first gives me the details of my email addresses and, underneath, the various Files are listed. The second 'column' is either the emails Inbox/Sent box.

Usually,when filing emails, I use the right-click method. Other times when, say, there are several to move to the same file, I use drag & drop between the columns which is usually successful. The same success for both Inbox/Sent emails.

This week the snag has occured with both Inbox/Sent i.e. that drag & drop removes an email but does not deliver it to the appointed file. Similarly with right-click: the emails it does move do not stay in the files, they quickly go missing.

Hope this clarifies the snag.

Kind regards, Tim

Unfortunately, I cannot duplicate that, as that work flow is common throughout Thunderbird users. From your post, this seems to have happened just recently. A new release version was announced today, and installing it may help. But that's just my guess.