Office 365 How to Prevent Access to Web Mail
Want to disable a single user or group of users from access email via the web portal? Its really easy so lets take a look:
1. Sign into the Exchange admin center https://outlook.office365.com/epc
Select the user or users you want to disable web email access for.
2. Press yes and confirm you want to disable web based email.
Now when the user or users log into the web portal they will have access to all other features such as Teams.
However when they click on the Outlook App they will get an error message because its now disabled.