Using Classic Outlook on Windows for personal email, calendar, and contact management
Same here, I've been using this feature for years and since a couple of months this feature is broken. I confirm that checking the outbox during the delay time seems to be the cause of the problem. Dragging and dropping to Drafts folder and then hitting send works every time but this workaround is very tedious and not ideal. Please fix this. This is a crucial feature for many!