Microsoft have finally added inking support to Outlook for the Surface Duo and Surface Duo 2. Update 4.2145.1 which has just rolled out enabled you to use a Surface Pen to create your email. There is a new pen icon in when composing an email, tapping the icon brings up the pen toolbar where you can select a pen, highlighter, pencil or eraser.
You can select colour and pen thinness from the pen menu. It’s taken a while for Microsoft to add the feature for Surface Duo and Surface Duo 2 owners but it’s good to see functional improvements to the device.