If you cannot add an account in the new Outlook in Windows 11/10, enable the account for New Outlook, clear the local Outlook state, etc.

How to add a shared mailbox in the Outlook app on iOS or Android Open the Outlook app. Tap your profile image, then select the settings cog. Tap Add email account > Add shared mailbox.

Launch Outlook and switch to the legacy client from the top menu. Relaunch the app. Click Outlook at the top and open Settings. Open Accounts. Select + at the bottom. Click Add an account.

Use “Accounts -> Email accounts -> Add account” to add further email accounts to the new Outlook. You can customize existing accounts with the “Manage” button for the respective account.

To add an email account to Outlook for Mac, open the program, click Tools from the menu bar, then select Accounts. Within the Accounts window that appears, click the + icon (Figure A).