Drag & Drop from email to desktop not landing at designated spot. Finder opening when dragging to desktop
Your "Show View Options" may have been changed recently to sort items by name or date or size or kind or label.


Click anywhere on the desktop (except on any file/folder)
Press Cmd+J (or use the mouse to go to the Finder's View > Show View Options menu)
In the Sort by: dropdown in the dialog, choose either None or Snap to Grid
Now you'll be able to drop files at specific locations on the desktop