Why has the categories option disappeared from my shared mailbox in Outlook New and can I restore it?

Is the missing category context menu in Outlook New shared folders a bug or a permanent feature change?

The recent removal of the “Categories” option from the context menu in Outlook New (version 1.2026.120.300) appears to be a regression affecting specific tenant configurations. Based on the user report from February 11, 2026, and similar historical incidents with Exchange Online, this issue often stems from how “New Outlook” (which relies on web-based architecture) handles the Master Category List (MCL) for delegated accounts compared to Classic Outlook.

Shared Mailbox Categories Missing in Outlook New: Diagnosis and Workarounds

Microsoft’s push toward the “Outlook New” client continues to introduce friction for enterprise workflows. A critical function for team collaboration—categorizing emails within Shared Mailboxes—has reportedly vanished for users on the latest February 2026 build (Version 1.2026.120.300).

IT administrators utilize Shared Mailboxes in Exchange Online to allow multiple team members to manage a centralized email address. When the categorization feature fails, workflows disrupt immediately. The issue described involves a sudden disappearance of the “Categories” command from the context menu (right-click menu) for one user, while another user on the identical build retains access.

The Technical Disconnect: Local vs. Server-Side

The root cause likely lies in how Outlook New synchronizes the Master Category List (MCL). Unlike Classic Outlook, which caches XML data locally, Outlook New relies heavily on direct API calls to Exchange Online.

When a user cannot see categories, two failure points usually exist:

• Permission Propagation Latency: The “Full Access” right allows a user to open the mailbox, but the “Editor” permission specifically controls the ability to modify item properties like categories. If the context menu is missing entirely, the client may be failing to validate these specific “Editor” rights during the session handshake.
• Automapping Glitches: Outlook automatically maps shared mailboxes to the user’s profile. This automapped connection is often “read-heavy” and can strip out advanced features like categorization to save bandwidth.

Diagnostic Steps for IT Administrators

Before waiting for a Microsoft patch, affected teams should test these isolation steps to confirm if the issue is client-side (app) or server-side (permissions).

Isolate with Outlook on the Web (OWA)

Direct the affected user to log into outlook.office.com. Open the shared mailbox via “Open another mailbox” in the top-right profile menu.

Result A: If categories work here, the permissions are intact. The issue is strictly the Outlook New client code.​

Result B: If categories are missing here too, the issue is an Exchange Online permission corruption. Remove and re-add the user’s delegation rights.

The “Add Account” Workaround

Automapped mailboxes are convenient but fragile. A proven fix for category syncing is to manually add the shared mailbox as a secondary account rather than relying on automapping.

1. Open Settings in Outlook New.
2. Select Accounts > Email accounts.
3. Choose Add Account and enter the email address of the shared mailbox.
4. When prompted for credentials, sign in with the user’s own credentials (since they have delegation rights).

This forces a direct Exchange connection, often bypassing the UI limitations of automapped folders.

Check the “Upgrade” Loop

Since one user on Windows 11 24H2 is unaffected, compare their “Release Channel.” Microsoft frequently A/B tests features. One user may be on a “Targeted Release” track that received a buggy code push earlier than the other. Verify if the working user has a slightly different build number or a pending update the broken user has already installed.

Community Verification Needed

This specifically impacts the context menu UI. We need to determine the scale of this regression.