My company has a security concern and they have requested to disable storing all offline cache copies of office 365 emails.
We use outlook 2016, thunderbird and the exchange server is office 365 tenant. We use different operating systems, such as mac/ubuntu/fedora/widnows to access emails which makes hard to stick to local group policy to block storing offline cache copies.
We are trying to disable storing emails offline. What I have tried is I have applied a policy using
"Outlook Web App policies" in ourlook 365 via https://outlook.office365.com/ecp/ "permissions" ----> "Outlook Web App policies" and disabled offline access in the below manner.
Unfortunately it works only for webaccess. As intended It will disable offline storing in https://outlook.office.com/owa/?path=/options/offlinesettings/mode/popup
If a user tries to enable offline access via https://outlook.office.com/owa/?path=/options/offlinesettings/mode/popup
this message will appear, which is as expected.
The problem lies with outlook and other clients such as thunderbird. "Outlook Web App policies" wont disable offline access for outlook/thunderbird etc.
It will still allow users to save offline copies in outlook/thunderbird etc.
So was looking for an viable alternative. and found this https://docs.microsoft.com/en-us/previous-versions/office/exchange-remote-connectivity/dd439383(v=exchg.80)
Set-CasMailbox MailboxName -MapiBlockOutlookNonCachedMode:$false
but again its only for onpremis-exchange according to this .
MapiBlockOutlookNonCachedMode seems not working for office 365.
Any viable option/advice to achieve above goal to disable storing all offline cache copies of office 365 emails.? Thanks a lot in advanced.