Outlook sync issue

Question

Hi everyone,

We are currently experiencing an issue with a shared mailbox in Outlook (desktop versions). Our team is using a mix of the newer Outlook experience and the classic version, but all are desktop users.

The problem is that updates in the shared inbox are not happening in real time. For example, when a new email arrives and one team member categorizes or takes action on it, the change is not immediately visible to others. This delay causes confusion, as team members cannot tell if someone is already working on an email or not.

We would like to understand:

• Is this expected behavior for shared mailboxes in Outlook desktop?
• Are there any settings or configurations that can improve real-time syncing?
• Would using a specific version of Outlook (all new or all classic) help resolve this issue?

Any guidance or best practices to ensure better real-time visibility across the team would be greatly appreciated.

Thank you!

Answer 1

For classic Outlook for Windows, what is described is not fully expected behavior; shared mailboxes should normally sync changes (new mail, flags, categories, etc.) without long delays. However, there are known issues and limitations that can cause delayed or inconsistent updates, especially with certain builds and with the new Outlook for Windows.

Key points from current known issues:

1. Classic Outlook shared mailbox sync issues

• There is a documented issue where shared mailboxes stop updating automatically and show “Updating this folder” in the status bar. In affected profiles, sync errors appear in the Sync Issues folder, and other symptoms (NDRs, calendar errors, archive issues) can occur.
• This issue was introduced with Version 2202 (Build 14931.20604) and later fixed by service and client updates, but existing Outlook profiles that became corrupt do not get fixed automatically.

Practical implications for the scenario:

• If any users are on classic Outlook Version 2202 (Build 14931.20604) or close to it and see “Updating this folder” on the shared mailbox, the profile may be in a broken state.
• In that case, the shared mailbox may not sync reliably in real time.

Recommended actions for classic Outlook desktop:

1. Verify build and channel
   • Check Outlook version/build and ensure it includes the fix (for Semi-Annual Enterprise Channel, Version 2202 Build 14931.20660 or later).
2. Check for profile corruption
   • In Outlook, open the Sync Issues folder for the primary mailbox and look for recurring sync errors related to the shared mailbox.
   • If present and the build is already updated, recreate the Outlook profile so the shared mailbox is re-added cleanly under the fixed client.
3. Confirm the shared mailbox is added correctly
   • Ensure the shared mailbox is added via Exchange/automapping or as an additional mailbox on the primary Exchange account, not via unsupported methods.
4. New Outlook for Windows shared mailbox sync behavior

• In the new Outlook for Windows, incoming emails in shared mailboxes added by automapping do not sync automatically in the same way as the primary mailbox.
• Users must manually trigger synchronization by selecting Sync on the ribbon or by selecting the folder.
• To get automatic sync and notifications for a shared mailbox in new Outlook, it should be added as an account (not only via automapping).

Practical implications for the scenario:

• Mixed use of classic Outlook and new Outlook can lead to different sync behaviors for the same shared mailbox.
• Users on new Outlook who only see the shared mailbox via automapping will not see changes in real time unless they manually sync or the mailbox is added as an account.

Recommended actions for new Outlook desktop:

1. For users who must see real-time changes in a shared mailbox:
   • Add the shared mailbox as an account in new Outlook (per “Manage shared mailbox settings in new Outlook”) so it syncs automatically and shows notifications.
2. For users who keep the shared mailbox only via automapping:
   • Use the Sync button or select the folder frequently to refresh.
3. Version alignment and best practices

• Using a single Outlook experience (all classic or all new) simplifies expectations but does not by itself guarantee real-time sync.
• For classic Outlook:
  • Ensure all users are on a build that includes the shared mailbox fix and recreate any profiles that show persistent sync errors.
• For new Outlook:
  • For teams that rely heavily on shared mailbox real-time visibility, ensure the shared mailbox is added as an account for all users who work in it.

Summary answers to the specific questions:

• Is this expected behavior?
  • Classic Outlook: No, long or inconsistent delays are not expected; known bugs and profile corruption can cause them.
  • New Outlook: Limited/triggered sync for automapped shared mailboxes is expected; automatic real-time sync requires adding the shared mailbox as an account.
• Settings/configurations to improve real-time syncing:
  • Classic Outlook: Update to a fixed build, check Sync Issues for errors, and recreate any corrupt profiles.
  • New Outlook: Add the shared mailbox as an account instead of relying only on automapping; otherwise, use the Sync button or folder selection to refresh.
• Would using a specific version (all new or all classic) help?
  • Aligning everyone on classic Outlook with a fixed build and healthy profiles can provide more consistent shared mailbox sync behavior.
  • If using new Outlook, ensure consistent configuration (shared mailbox added as an account) across the team to get near real-time updates.

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References:

• Shared mailbox is not automatically refreshing for new email in Outlook
• Sync a shared mailbox in new Outlook

Answer 2

Hi @hira siddiqui 

Besides the response from the Q&A Assist, I would like to share the insights I have gathered so far based on my own testing between the Classic Outlook and the New Outlook desktop versions. 

From my testing, when performing actions such as categorizing emails in a shared mailbox folder, the changes still require a short period of time to synchronize. The update is not instantaneous, and I usually need to click on another email or switch to a different folder and then return to the original item for the change to reflect properly. 

If the synchronization delay has an impact on your workflow, there are some alternative options you may want to consider, depending on your needs. 

• Microsoft 365 Groups:  This provides a shared Outlook inbox, shared calendar, SharePoint file storage, and Planner integration, and it can also be connected to Microsoft Teams. 
• Dynamics 365 Customer Service:  If your main requirement is real-time ownership visibility, work pickup, routing, and status tracking, Dynamics 365 Customer Service offers more purpose-built functionality through queues. For additional reference, you may find the following resources helpful:
  • Welcome to Dynamics 365 Customer Service | Microsoft Learn 
  • Use queues to organize, prioritize, and monitor work | Microsoft Learn 

I hope this provides helpful context and additional insight. If you have any updates or further observations, please feel free to share them. 

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