By default Office 365 (Exchange Online) allows users to enable an offline cache of all their email when using OWA. As you can imagine this doesn’t fit all corporate security models because OWA can be accessed anywhere and then the email can be cached on any computer. This post will cover how to edit the default Outlook Web App policy so that you can disable this feature.
For more about the user side of the experience and how to turn on/off at that level, please reference the Microsoft KB below.
Disable Outlook Web App (OWA) Offline Cache Mode at the organizational level
Login to the Office Admin Center
On the left navigation menu, click Admin Centers
In the Exchange Admin Center, click Permissions on the left navigation menu
Click Outlook Web App policies
Double click OwaMailboxPolicy-Default policy
- If you have more than one policy, you may have to edit all the policies. Chances are that if you have more than one policy you also know what all those policies are for and will edit accordingly.
On the Outlook Web App policies window, click Offline Access
Now when we try to enable offline access for OWA under the user account, the user is blocked from doing so.