This "Allow in-cell editing" is available in Outlook 2013. The attached image shows you this feature. I don't leave it turned on as that could potentially change subject lines by accident. I only turn it on when it is needed. It really isn't a big deal but I was hoping for a simple toggle to add to the Quick Access Toolbar. In the second attached Image, you will see the "Other Settings" button that was added to the Quick Access Toolbar and from that button when selected you get what is seen in the first image titled Allow in-cell editing.png
The image OtherSettings.png is a combination of the normal Outlook with the Options page overlaid. You should be able to see this. At the very top of the normal Outlook, you see the Quick Access Toolbar to the left of the drop-down arrow.

Attached Images

	Allow in-cell editing.png (19.6 KB, 6 views)
	OtherSettings.png (46.4 KB, 5 views)