Mail: Allow directly open embedded images
A workflow/feature I grew quite accustomed to from Geary and other email clients is being able to double-click embedded/in-lined media like pictures and have them open in the system-default program.
Currently, we have to right click, save as, give it a name, choose a location, switch to the directory, open the file to view it.
A much easier/better workflow would be to have Evolution save it to an internal cache/tempfile and directly launch the appropriate program when you double-click on it.