Hello everyone and thank you for taking the time to request this feature. As part of our investigation on adding this capability, we ask that you please help us gather additional information on how you use Pin. This helps us to prioritize and design the feature to be exactly what you need to get more done!
Please use the below link to access a short survey about Pin:Mo commented
Please do this on the Outlook 2016. Its on the web based version, but not desktop which is weird.