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Outlook 365 Shared Mailbox not synchronizing

Anonymous
2022-01-24T13:57:20+00:00

We are using O365for our 303 users. We are encountering an issue with the Cached Mode of Outlook when it comes to Shared mailboxes.

Many users are members of 4 shared mailboxes or more, the received Emails are no longer appearing in the inbox folders of the shared mailboxes (this is not thze case for the primary Email address of the user). The only way to synchronize the Emails is to go to:
Send/Receive --> Update Folder (even pressing Send/Receive all Folders does not work)

This is not practical for the users, and we want this to occur automatically as it is supposed to be. We went through the following troubleshooting steps:

  1. Check shared mailbox accessibility via the Outlook web app --> Accessible without problems
  2. I went to File> Office Account> Update Options> Update Now, Outlook is up-to-date (Version 16.0.14729.20254).
  3. I re-created the .ost file --> Problem persists
  4. I cleared Offline items --> Problem persists
  5. I started Outlook in safe mode (ClickStart > Run> type outlook.exe /safe> clickOK) --> Problem persists
  6. I tried Enable/Disable Cached Exchange Mode --> Problem persists
  7. I checked Enable “Download shared Folders” and “Public folders favorites” --> Problem persists
  8. I added the CacheOthersMail DWORD Value and set it to HKEY_CURRENT_USER\Software\Microsoft\Office\xx.0\Outlook\Cached Mode in the Windows Registry (KB: https://docs.microsoft.com/en-US/outlook/troubleshoot/data-files/by-default-shared-mail-folders-are-downloaded-in-cashed#method-1---manual-modification-of-the-windows-registry) --> Problem persists
  9. I uninstalled the whole office package and re-installed it again --> Problem persists.

Two approaches worked but do not fullfill our needs because every user is a member of many shared mailboxes, and we would not be able to do this process for each user:

  1. Link a shared mailbox to a new Outlook profile --> Emails are automatically synchronizing
  2. Create a profile with the user Email address and all the shared mailboxes he is a member of (tried only with 1 shared mailbox)

It would be very helpful if you could support with this.

Thank you in advance.

Outlook | Windows | Classic Outlook for Windows | For home

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  1. Anonymous
    2022-01-25T16:02:48+00:00

    Hi Roady,

    1. I cannot reduce the number of shared mailboxes per user, because they need to access all of them (and it is by default configured by automapping, they appear automatically in Outlook, this is what we need anyway).
    2. For each shared mailbox there are no more than 30 folders approximately.

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  2. Anonymous
    2022-01-25T16:00:17+00:00

    Hi Vaidya Darpan,

    I implemented the requested scenario:

    1. I removed automapping for shared mailbox via PowerShell command
    2. I added the shared maibox to outlook manually as described above

    Result: Emails are synchronizing

    But as I explained in the post, we have many shared mailboxes per user, so we cannot do this process for 300 users and 8 shared mailboxes for each user.

    How can we proceed further please?

    Thank you so much for your support.

    Best Regards

    Aicha

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  3. Robert Sparnaaij [MVP] 18,316 Reputation points MVP Volunteer Moderator
    2022-01-24T16:26:56+00:00
    • When you reduce the amount of mailboxes that are being connected to, does it start to work again then? (does require a restart of Outlook)
    • How many mailbox folders (not mailboxes) in total are we talking about here?

    It could be that you are running into connection limits.

    See: Performance and synchronization problems when you work with folders in a secondary mailbox in Outlook (microsoft.com)

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  4. Anonymous
    2022-01-24T15:31:30+00:00

    Hi Darpan,

    thank you for your quick response.

    • Yes users are able to receive email message on shared mailbox account on Outlook web app (https://outlook.office.com) side properly from the server.
    • The Shared mailbox are added as automapping once the user profile is created. Even if adding it manually solves the problem, it would not be feasable in our case (we have many users and many shared mailboxes per user).
    • I have global admin rights, I can run the commands in Powershell. But if this works, how we proceed further?

    Thank you so much for your support.

    Best Regards

    Aicha

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  5. Anonymous
    2022-01-24T14:33:56+00:00

    Hi AichaGarci28,

    Thank you for sharing such information with us. We will highly appreciated your kind cooperation and patience in our forum community.

    • At once, may I please re-confirm if users can receive email message on shared mailbox account on Outlook web app (https://outlook.office.com) side properly from the server?
    • May I please re-confirm whether the Shared mailbox has added as automapping or manual process in to the Outlook?
    • At initial stage, please kindly try to check below kind of result scenario with one user and see if it makes any different result scenario or not.

    If the Shared mailbox has added as automatic process, at once you have to disable or remove automapping for shared mailbox via PowerShell command. Here is the detailed information article: How to remove automapping for a shared mailbox in Outlook for Office 365

    After disabling automapping for your shared mailbox account, you have to add shared mailbox as manual process under Outlook in user’s mailbox account via using method 3 from this mentioned information article and try to check such kind of result scenario. First, Make sure that automapping is disabled for the shared mailbox account.

    Below are some detailed steps information to add shared mailbox as manual process:

    Open Outlook > File > Info > Account Setting > Account Settings > Select your user mailbox account > click on New tab > type shared mailbox email address > click on Connect > now, you have to type your user email account address and password via selecting Sign in with another account option in next Sign in page Window page > click on Done > Re-start Outlook and see the result.

    Note: to run PowerShell command, if you are not global IT admin, please contact them in your organization to perform such action from their end.

    Please kindly feel free to contact us and provide us some above requested information for further analysis.

    Stay safe and healthy.

    Regards,
    Darpan

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