Outlook Mention Notification @Name Not Highlighting: How to Fix

When you type @Name in an Outlook email, the name should appear highlighted in blue and a notification should appear in the recipient’s inbox. If the name does not highlight or the mention notification fails to trigger, the feature is not working as intended. This problem usually occurs because the Outlook client is out of date, the Exchange policy blocks mentions, or the recipient’s version of Outlook does not support the feature. This article explains the root causes and provides step-by-step fixes to restore @mention highlighting and notifications.

Why @Name Mention Highlighting Stops Working in Outlook

The @mention feature in Outlook relies on the Exchange server to process the mention and add the notification flag to the recipient’s mailbox. When the feature fails, the cause is usually one of these three scenarios:

Outdated Outlook client. Older builds of Outlook 2019, 2021, or Microsoft 365 do not include the latest mention rendering code. A missing update can break the blue highlight and the notification banner.

Exchange mailbox policy blocks mentions. Administrators can disable the @mention feature through the OWA mailbox policy in Exchange Online or Exchange Server 2019. If the policy has MentionEnabled set to $false, mentions will not work.

Mailbox synchronization mode conflict. Outlook in Cached Exchange Mode with the download shared folders option turned off can prevent the mention notification from appearing in the recipient’s inbox. The mention flag is stored in the server-side message, and some cache settings hide it.

Less common causes include a corrupted Office installation, a damaged Outlook profile, or a third-party add-in that intercepts the mention event.

Steps to Restore @Name Highlighting and Notifications

Follow these steps in order. Test the @mention feature after each step by composing a new email, typing @ followed by a contact name, and sending it to yourself or a test account.

Step 1: Update Outlook to the Latest Build

1. Open Outlook and go to File > Office Account
   In the right panel, click Update Options and then select Update Now. Outlook will check for updates and install them automatically.
2. Restart Outlook after the update completes
   If the update requires a restart, close and reopen Outlook. Verify the version number by going to File > Office Account > About Outlook. The build number should be at least 16.0.15601 for Microsoft 365 or the latest cumulative update for Outlook 2021.
3. Test the @mention feature
   Create a new email, type @ and a contact name. If the name turns blue and shows a pop-up with the contact card, the update fixed the issue.

Step 2: Check Exchange Mailbox Policy for Mentions

This step requires administrator access to Exchange Online or Exchange Server 2019. If you are not an admin, ask your IT department to perform this check.

1. Connect to Exchange Online PowerShell or Exchange Management Shell
   Open Windows PowerShell as Administrator and run Connect-ExchangeOnline for Exchange Online, or open Exchange Management Shell for Exchange Server 2019.
2. Check the default OWA mailbox policy
   Run the command: Get-OwaMailboxPolicy | fl Name,MentionEnabled. If MentionEnabled is $false, mentions are disabled.
3. Enable mentions in the policy
   Run: Set-OwaMailboxPolicy -Identity "Default" -MentionEnabled $true. Replace “Default” with the name of your policy if it is different.
4. Apply the policy to user mailboxes
   Run: Set-Mailbox -Identity "user@domain.com" -OwaMailboxPolicy "Default". Repeat for each affected user or use a filter to apply to all users.

Step 3: Switch Outlook Mailbox Mode

1. Open Outlook and go to File > Account Settings > Account Settings
   Select your Exchange account and click Change.
2. Change the Cached Exchange Mode setting
   In the Offline Settings section, make sure Use Cached Exchange Mode is checked. Then click More Settings and go to the Advanced tab. Under Cached Exchange Mode settings, check Download shared folders. Click OK.
3. Restart Outlook
   Close and reopen Outlook. The mailbox will synchronize again. After the sync completes, test the @mention feature.
4. Alternative: Switch to Online Mode
   If the problem persists, go back to Account Settings > Change and uncheck Use Cached Exchange Mode. Restart Outlook. Online mode forces a direct connection to the Exchange server and can resolve mention notification issues.

Step 4: Repair Office Installation

1. Open Control Panel and go to Programs > Programs and Features
   Find Microsoft 365 or Microsoft Office in the list. Right-click it and select Change.
2. Choose Quick Repair first
   Select Quick Repair and click Repair. Follow the prompts. This will fix corrupted files without removing your data.
3. If Quick Repair does not work, run Online Repair
   Go back to Programs and Features, right-click Office, select Change, and choose Online Repair. This will download and reinstall Office completely. A stable internet connection is required.

If Outlook Still Has Issues After the Main Fix

@mention works in Outlook for Windows but not in Outlook for Mac

Outlook for Mac uses a different rendering engine. As of version 16.78, @mention highlighting is supported. Update Outlook for Mac through the Microsoft AutoUpdate tool. If the issue persists, remove and re-add the Exchange account in Outlook for Mac.

@mention works in new email but not in replies or forwards

This is a known limitation in Outlook. The @mention feature is designed to work only in new messages. In replies and forwards, the name will not highlight. To mention someone in a reply, type their full email address manually or use the To field.

Notification banner shows but name is not highlighted

This indicates that the Exchange server processed the mention correctly, but the Outlook client failed to apply the visual highlight. The fix is to update Outlook to the latest build as described in Step 1. If the problem remains, reset the Outlook navigation pane by right-clicking the folder pane and choosing Reset Navigation Pane.

Outlook @Mention Feature: Cached Mode vs Online Mode Behavior

Item	Cached Exchange Mode	Online Mode
Highlight rendering	Depends on local cache sync	Rendered from server directly
Notification delivery	Requires download shared folders enabled	Always delivered
Offline mention support	Works if previously cached	Not available offline
Best for	Users with slow or intermittent connections	Users who need instant mention delivery

The core difference is that Online Mode sends and receives mention data in real time from the Exchange server. Cached Exchange Mode stores a local copy and must have the download shared folders option turned on to include mention flags. If you frequently send @mentions and need instant visual feedback, Online Mode is more reliable.

After applying the steps in this guide, the @Name mention should highlight in blue and trigger a notification in the recipient’s inbox. If the issue persists, verify that the recipient also uses a compatible Outlook version. As an advanced step, you can enable diagnostic logging in Outlook by adding the registry key HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Options\Mail with a DWORD value EnableMentionLogging set to 1. This creates a log file that IT can analyze to pinpoint the exact failure point.