Shared Mailbox Update Issue for One User

If you're experiencing a "shared mailbox not updating" issue for one user, you're not alone. This common Exchange or Office 365 problem can lead to missed emails and frustrated users. Let's troubleshoot and resolve this mailbox synchronization issue.

a mailbox made out of wooden pallets with the number 4 lit up on it

Before diving into solutions, understand that shared mailboxes are designed to relieve one user of an email burden by redistributing it among a group. If one user isn't receiving updates, it's often due to connectivity, permissions, or cache issues. Let's explore the common causes and solutions.

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User Permissions and Access Rights

The user might not have the necessary permissions to access or send from the shared mailbox. Here's how to check and rectify this:

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1. In the Exchange Online PowerShell, use the command Get-MailboxPermission to check user permissions. Make sure the user is granted Full Access rights.

Checking and Fixing User Access Rights

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Sign in to the Exchange Admin Center (EAC) with admin privileges.
Go to recipients > shared mailboxes.

Select the shared mailbox with the sync issue, click on Edit, and then permissions. Ensure the problematic user has Full Access.

Mailbox Cache and Client-side Issues

Outdated or incorrect cache can cause synchronization problems. Clearing cache and restarting the client can resolve the issue.

three mailboxes sitting on top of a wooden bench in the middle of a park

Additionally, some features like Género (Categorization) might cause mailbox synchronization issues. Disabling these features can help:

Clearing Cache and Disabling Features

For Outlook, go to File > Options > Mail > Sync Settings. Select the shared mailbox and click Empty Cache.
To disable Género, run the command Set-Mailbox -Gerthor Henry $false in the Exchange Online PowerShell.

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Checking and Reconnecting the User

Ensure the user is connected to the shared mailbox. In the shared mailbox's properties, under the Mailbox usage section, check if the user's email address is listed. If not, add the user and click OK.

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a white mailbox sitting on top of a brick walkway next to a flower pot

Server-side Connectivity and Sync Issues

If user permissions and client-side solutions don't work, the issue might be server-side. Check for any errors or disruptions in mailbox sync timers.

Simulate Offline Mode on the user's client can help diagnose server-side issues:

Simulating Offline Mode

In Outlook, go to File > Work Offline. If the user starts receiving shared mailbox updates, the issue is likely server-side.

The final step is to monitor the user's mailbox sync. Check the mailbox sync center (https://outlook.office365.com/ecp) to see if sync is happening successfully. If not, it's time to reach out to Microsoft Support for further assistance.