If you are getting the error that your Mail/Outlook settings are out of date in the official Mail app in Windows 10, then this post is for you.
There are a few solutions to this. The first one is to outright¬†disable this notification from showing up on the screen. And, the second one is to reset and reinstall the mail app on your computer.
Disabling the notification is quite simple. Go to the Settings app > System > Notifications & actions. Scroll down a bit, and turn off the notifications for the Mail app. Do the same for the Calendar app too if the error says that the Calendar settings are out of date on your computer.
Of course, this will disable all the notifications from the Mail app and not only the one you are trying to get rid off. So, this is a temporary solution. The more effective way to fix this is to reset the app.