Switch between Mail and Calendar by selecting Switch to mail or Switch to calendar on the lower-left side of the window. No need to add the same account twice-when you add it to one app, the other app automatically connects to the same account. To add more accounts, return to Settings. Your mail and calendar will automatically start syncing. Select Manage accounts > Add account, then choose an account, and follow the instructions. In the Mail or Calendar app, select Settings at the lower left. If this is the first time you're opening either Mail or Calendar, follow the instructions on the Welcome page. You've found the apps, now make them useful by adding your accounts. To open them, search for Mail or Calendar on the taskbar, and select the icons from the search results. Windows 10 has built-in Mail and Calendar apps.
