Moving a message with a keybind can easily be done accidentally, and then pretty hard to figure out where it went. Enable an undo for these operations (might make sense for other things as well).
List of undoable things:
+1
Would also be nice for :delete.
I'm pretty sure you can't undo a delete, it's gone. What you can undo is
:move Trash.
On the other hand, we shouldn't just have undo last. If we can undo the last one, we can just as easily have an undo stack, with I guess an
undo-history-sizeconfiguration option.