In this blog post, I’ll show you how to enable Offline Access In Outlook Web App (OWA) with Exchange Server 2016 or Exchange Online.
About Offline access
Offline Access allows Outlook Web App users to keep access their mailbox while they are offline and not connected to the network or the Internet.
Offline access stored 3 days or 150 items of each selected folder on the computer so when the computer goes offline these items are available for access until the network comes online.
By default the Inbox and draft folder are available for offline access plus another 5 folders, however, attachments are not available for offline access.
Changes made offline will be synced when connection resumes.
To enable Offline access on Outlook Web App from the setting menu click on Options
In the Options page go to General -> Offline Settings and tick the box
Follow the prompts
When done, you will have the option to add more folders to the Offline folders list
Offline access will save OWA items for IE in the folder below on the computer
C:\Users\username\AppData\Local\Microsoft\Internet Explorer\Indexed DB
If using chrome data will be located
Disabling Offline access From Exchange Server
You can disable Offline access to all users In the organisation using the cmdlet below from Exchange Server.
The line below will disable it on the OWA Virtual directory level to all users
set-OwaVirtualDirectory "ex16\owa (default web site)" -AllowOfflineOn nocomputer -Verbose
The line below will disable it on the OWA mailbox policy
Set-OwaMailboxpolicy default -allowofflineon nocomputers