I use Windows so the notification actions are: Reply, Flag or Delete. I use Delete often for junk mail or unimportant notifications, but I never use Reply or Flag. However, I am always wishing there was a "Mark as Read" option. For example, if I place an order for something I will undoubtedly receive an order confirmation. I already know what it says so I have no need to read it again so I want to mark it as read. To do that currently I have to open the email which takes a few moments, or I can dismiss/ignore the notification and then later I'll see the same email again.

I never use Reply because I usually want to read the full original email before replying and I never use Flag because my workflow is to use the Read status mainly and only use Flag for important emails that I want to reference later - I wouldn't decide that based on a notification.

In general, it would be great if the buttons that are presented in the Windows Action Center notifications were customizable as the ones given by default are not very useful for the way I use email.