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
    2021-09-10T17:33:53+00:00

    For the interested folks.

    This is the answer I got from Microsoft. They are planning to release a fix on Sept. 10th 2021 at 8:30PM UTC (4:30PM EST)
    ________________________________________________________________________________
    Title: Users can't add shared mailboxes via the Outlook mobile app

    *User Impact: Users are unable to add shared mailboxes via the Outlook mobile app.**More info: Outlook desktop and Outlook on the web are unaffected.Users will encounter the following error when attempting to add shared mailboxes via the Outlook mobile app:"Authentication Failed: That didn't work. You may not have the right permissions to add this mailbox or the mailbox doesn't exist."**Current status: We've determined that the reversion of the offending change across the affected environments requires additional validation and processing time, and we now anticipate resolution by Friday, September 10, 2021.**Scope of impact: Any user attempting to add shared mailboxes via the Outlook mobile app may be impacted.Start time: Tuesday, August 24, 2021, at 7:00 AM UTCEstimated time to resolve: We expect the change will be reverted and the user impact will be mitigated by Friday, September 10, 2021.*Root cause: A recent update intended to optimize the error code for disabled accounts incidentally introduced an incorrect logic and caused impact. Next update by: Friday, September 10, 2021, at 8:30 PM UTC

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  2. 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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  3. Anonymous
    2021-09-13T05:58:05+00:00

    On the Office 365 admin page - Health - Service health - advisories - Users can't add shared mailboxes via the Outlook mobile app

    Or search for advisory EX284109.

    Current status: The reversion of the offending change has completed the validation process, however this change will take some time to saturate across all affected environments. Users will incrementally experience mitigation as the saturation continues, and we expect completion for all users by Monday, September 13, 2021.

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  4. Anonymous
    2021-09-10T08:26:46+00:00

    Well Microsoft,

    It seems I'm not the only one with this problem and the Outlook for iOS or Android support team is lacking any support in this matter.

    Please escalate it to the right department or let someone of the  Outlook for iOS or Android support team join in this conversation.

    Contact via the mobile app is tedious and they'll give you the runaround.

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  5. Anonymous
    2021-09-09T21:21:31+00:00

    same issue here IOS 14.7.1

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