Private emails not being shown in Outlook client


I came across a known bug that just started affecting us is probably affecting others but they may not have noticed yet.


When external senders send emails with the sensitivity set to “private”, they do not appear in Outlook under the shared mailboxes. The only way we found this out was that a user who was a member of a shared mailbox opened a ticket with us saying that the unread count was incorrect. After we logged into her OWA and opened the shared mailbox via the web, it showed all the emails that were not in Outlook. After looking at the missing emails in OWA we noticed the emails marked “This message has been marked as Private.” Are the ones missing. In our case the sender was using Mimecast which is the same as the Spiceworks link below.


That lead me to Googling and it’s been a known issue for some time but I couldn’t find a good solution, so I opened a 365 case and they confirmed there is no known fix for this which shocked me.

Here are a few links to other having that problem:


The only workaround that seems promising is this one here which involves converting the shared mailbox to a standard mailbox with a license, logging into it directly and adding the “members” as delegates with the check box the allow delegates to see private items checked, then convert back to a shared mailbox.


The MS tech said that there will be an official fix when the issue get’s enough votes here so please vote




4 Replies

That's known indeed, and the solution is what you found - add the users as delegates and make sure to tick the "Private items" checkbox. This can be done programmatically via EWS, or you can toggle the corresponding flag via the Set-MailboxFolderPermission cmdlet and the -SharingPermissionFlags parameter. I'd stick with using EWS.

Then it will work once converted back to a shared mailbox right?

As long as they have the "Can see private items" flag toggled.

Alternatively you can create a flow in MS PowerAutomate (former MS Flow) that will change sensitivity from "private" to "normal" for each message delivered to the shared mailbox.