Outlook for Mac won't let me add a shared mailbox - but webmail/outlook, iphone outlook, and ipad outlook will - WHY? HELP!!

Question

I have a shared mailbox setup on our server that I have been able to add to my iphone outlook, my ipad outlook, and my webmail outlook, but...can't find it on my Outlook for Mac.

Anyone have any suggestions on what to do? Thank You!!!

Answer 1

Outlook for Mac handles shared mailboxes differently from Outlook on the web and mobile, so the shared mailbox will not just appear automatically in all cases.

Use one of these supported methods, depending on how the shared mailbox is configured and what permissions are granted:

1. If the mailbox is a shared/delegated mailbox (common case)

• In Outlook for Mac, go to Tools > Accounts and select the primary account that has access to the shared mailbox.
• Select Delegation and Sharing.
• Go to the Shared With Me tab.
• Select + and add the shared or delegated mailbox.
• Alternatively, use File > Open > Shared Mailbox to open it.

2. If granted Full Access to the shared mailbox in Exchange Admin Center

• Go to Tools > Accounts.
• Select the + sign to add an additional Exchange account.
• In E-mail address, enter the shared mailbox address.
• Under Authentication, enter the primary user credentials (not the shared mailbox’s own password).
• Optionally enable Sync shared mailbox so it syncs automatically.

3. If adding it as an additional mailbox using its own credentials

• Go to Tools > Accounts.
• Select + > New Account.
• In E-mail address, enter the shared mailbox address.
• Under Authentication, enter the shared mailbox’s own credentials.
  • Note: This is treated as an additional Exchange account, not as a shared mailbox, and some shared-mailbox features/add-ins may not be fully supported.

Additional notes that explain the difference from web/iOS/iPadOS:

• Outlook for Mac does not support Auto-mapping of shared mailboxes, so they will not appear automatically just because permissions exist; they must be added using one of the methods above.
• Outlook for Mac currently supports only Full Access permissions for shared mailboxes as a fully supported configuration; other permission combinations may work but are not fully supported.
• If only folder-level permissions (Inbox/Calendar/Address Book) were granted, use File > Open > Other User’s Folder and choose the appropriate folder type.

If an “Account already exists” error appears when trying to add the shared mailbox via Add email account, close that window and add it instead via Delegation and Sharing > Shared with me > +.

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References:

• Open a shared Mail, Calendar or People folder in Outlook for Mac
• Outlook for Mac “Account already exists” error
• Implement shared folders and shared mailbox scenarios in an Outlook add-in

Answer 2

Hi @Mark Galloway  

Thank you for posting your question in the Microsoft Q&A forum.  

In New Outlook for Mac, shared mailboxes do not always auto‑map and may not appear even though they work in Outlook on the web and mobile apps. 

First, please confirm with your IT administrator that you’ve been granted the necessary permissions in the Microsoft 365 admin center: Teams & groups > Shared mailboxes > select the mailbox > Manage mailbox permissions > confirm you have Read and manage permission.

Once permissions are verified, try adding the mailbox manually: Outlook > Settings > Accounts > Advanced… > Delegates > Open these additional mailboxes > + > Add your shared mailbox > OK. 

If the mailbox still doesn’t appear after these steps, do you see any error messages? If so, could you share a screenshot in a private message so we can better understand the issue and suggest further troubleshooting? 

Please know that while our initial response might not resolve the issue right away, your input is incredibly valuable. With a bit more detail, we’ll work together to find the best solution for you. 

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