Notification settings are per-account in the Email app. Go into Email, tap settings, go to options, scroll down. Each account will have a separate notification toggle for sounds/banners.
The way notifications is extremely finicky on Win10. I figured out to get notifications working for email I had to pin my Hotmail account within Outlook. Only then could I get notifications.
Same with custom text sounds for contacts. I had to switch the universal text notification sound to default first, then select a custom sound within the person's profile. Way more complicated than it used to be or needs to be.