unable to open shared mailbox

Question

Hi All

One of my user is unable to open shared mailbox in new outlook for MAC.

in old outlook for MAC-->Tools--Accounts--Advanced--Select Delegates--Open these additional mailboxes: Added shared mailbox and it is working fine.

In new outlook for MAC-When user tries open Shared mailbox-user is getting error

Cannot open this mailbox-->This mailbox has already been added.

Answer 1

Hi
Glenn Maxwell

In some cases, cached credentials may be causing authentication issues. Clear the cached credentials for the account in Outlook.

here is the path

Go to "Outlook" > "Preferences" > "Accounts."

Select the account associated with the shared mailbox, and click on "Advanced."

Click on "Remove from Vault" to clear cached credentials.

Close and reopen Outlook and try accessing the shared mailbox again.

Hope this solves the issue, kindly accept the answer if it it thanks.

Answer 2

Hi @Glenn Maxwell

When attempting to open a shared mailbox in the new Outlook for Mac, it indicates that it was maybe added in a different place or with different settings. Here are some troubleshooting measures you can take with your user:

Check Existing Shared Mailboxes

Remove and Re-add the Shared Mailbox

Use Alternate Method (Choose File > Open > Other User's Folder.... Select Inbox from the list of Folder Types. Enter the name of the person who granted you access to the shared mailbox in the Search box. Click Open after selecting the person's name from the search results.)

Update Outlook

Contact Microsoft Support

Also, check these helpful links - 

Open a shared Mail, Calendar, or People folder in Outlook for Mac: https://support.microsoft.com/en-us/office/open-a-shared-mail-calendar-or-people-folder-in-outlook-for-mac-6ecc39c5-5577-4a1d-b18c-bbdc92972cb2

Unable to add shared mailbox in New outlook for Mac - Workaround Found: https://answers.microsoft.com/en-us/outlook_com/forum/all/unable-to-add-shared-mailbox-in-new-outlook-for/f9c3a51b-e469-4017-b44f-357eb81874b3

Answer 3

Dear @Glenn Maxwell ,

Welcome to our Q&A forum!

You mentioned that you can add shared mailbox from older outlook for Mac, but this feature can't be used in new outlook for mac.

You can compare your process with Open a shared Mail, Calendar or People folder in Outlook for Mac . If there is something different, you can try again.

If you still meet the same problem, please be kindly to use Outlook on the web to try and check whether you will meet the same problem. You can try it according to Open and use a shared mailbox in Outlook on the web.

If you can successfully add and open it, it may have something wrong with your outlook client. Please be kindly to use safe mode to open Outlook and check whether the problem persists in this way. Here are the steps:

Select Apple menu > Shut Down from your Mac’s menu bar>Wait 10 seconds after your Mac has turned off>After restarting your Mac, hit and hold the Shift key>When you see the login window, release the Shift key>Here click on “Macintosh HD”>Then proceed to login to the user’s account>Finally, Outlook may be used.

And you can try deleting/re-creating profile to check whether the problem can be solved.

If none of the above suggestion helped, this issue maybe related to a feature not working in new Outlook for mac. So I sincerely suggest you get help from in-app support. There are engineers who are especially responsible for issues about Outlook for mac to provide you further help.

---

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment". 

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.