Can't open Shared mailbox on mobile device, works on every other client.

Anonymous
2021-06-15T13:20:37+00:00

We want to share mailboxes with 'Least privilege' principle.

So when creating a shared mailbox instead of making users Owner we want to assign only permissions on the necessary folders.

With a PowerShell session to Exchange Online we make the following changes:

Add-MailboxFolderPermission -Identity SharedMailboxTest:\ -user ******@contoso.com -AccessRights Reviewer

Add-MailboxFolderPermission -Identity SharedMailboxTest:\Inbox -user ******@contoso.com -AccessRights Reviewer

This works fine with Outlook Web App and Outlook desktop client. We can add the shared folder and read the messages.

But when we try to add a shared folder on a Outlook Mobile client we get an error:

Authentication failed

That didn't work. You may not have the right permissions to add this mailbox or this mailbox doesn't exist.

Also added permission directly on the mailbox:

Add-MailboxPermission -Identity SharedMailboxTest -User ******@contoso.com -AccessRights ReadPermission

But that didn't make a difference.

It must be possible to delegate folder permissions. It works for default clients, but it refuses to work on mobile Outlook unless I give the user Owner permissions, but that is not 'Least privilege'.
What I'm I missing here or did I stumble on a bug in Outlook Mobile?

(It has to be Outlook mobile client on cell phones)

Outlook | Windows | Classic Outlook for Windows | For home

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  1. Anonymous
    2021-06-25T07:01:31+00:00

    Well that was a very interesting case with the support on Outlook Mobile.
    As said above, it took me more than 15 minutes to enter all information to get a simple answer that it isn't supported.

    You can't even answer, call is gone in the mobile client!

    And it is possible, if assigned Ownership.

    It's also in their own support: How do I add a shared mailbox to my mobile device?

    So, maybe one of the Microsoft employees could wake someone up at the Outlook Mobile team and ask them to contact me?
    Would be appreciated.

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  2. Anonymous
    2021-06-16T07:10:02+00:00

    Hi Darpan,

    Thank you for your answer, but given the link you provide me, you judge me to quickly.

    When I add Owner rights on the mailbox people do get access with the mobile client, it's only with specific (Least privileged) access rights that the action fails. It's a combination of Exchange Online access rights with the mobile client.

    So it's a little simplistic to send me of to the dedicated Outlook for iOS or Android support team.

    But if that's the way it works in this community I will post the issue there, hoping not to get send back and forth...

    (Update: Well it has cost me about 15minutes to get the story in the support chat on the mobile client. Only chat is possible, messages are limited and completely messed up when you copy/past from an email. Not a very nice experience, some progress to achieve there!)

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  3. Anonymous
    2021-06-15T15:10:00+00:00

    Hi Ron,

    Have a good day. Thank you for posting in the Microsoft Community.

    As per your mentioned description about “Can't open Shared mailbox on mobile device”, since we have dedicated Outlook for iOS or Android support team, which is specializing to handling Outlook for mobile device related issues. So, we would recommend you to please contact to this mentioned dedicated support team to get further assistant and particular information. They will further assist you about your mentioned issue concern.

    Regards,

    Darpan

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