This is because when you drag and drop an email to a folder, it expands the folder so you’re able to see all subfolders and be able to drop the email in them.
However I agree that there should be a timer if you only want to drop the mail in the root folder, not the subfolders. I will file this as a feature request for our developers.
Yes, it would be great if eM Client automatically unexpanded a folder once the message has been dropped (that’s how it works in Outlook).
I am having the same problem. Very frustrating – bad UX.