Disable shared mailbox caching OST

Configure the registry by using a Group Policy setting

The registry key value that is required to change the default shared folder caching behavior in Outlook 2010 or later versions can be configured by using a Group Policy setting

Outlook 2013 or later versions

The default Group Policy template files for Outlook contain the policy setting that controls this functionality. These are Outlk16.admx and Outlk16.adml for Outlook 2016 and Outlk15.admx and Outlk15.adml for Outlook 2013. To deploy this setting by using the Outlook Group Policy template, follow these steps:

1. 1. Download the following file from the Microsoft Download Center:
      Office 2016: http://www.microsoft.com/en-us/download/details.aspx?id=49030
      Office 2013: http://www.microsoft.com/download/details.aspx?id=35554
   2. Extract the admintemplates_32bit.exe or admintemplates_64bit.exe file to a folder on your disk.
   3. Copy the file appropriate to your version of Outlook to the C:\Windows\PolicyDefinitions folder.
      Office 2016: Outlk16.admx
      Office 2013: Outlk15.admx
   4. Copy the file appropriate to your version of Outlook to the C:\Windows\PolicyDefinitions\xx-xx
      Office 2016: Outlk16.adml
      Office 2013: Outlk15.adml
      where xx-xx is a Language Culture Name. For example, for English (US), the Language Culture Name is en-us. For more information about Language Culture Names, visit the following Microsoft web site: http://technet.microsoft.com/library/ee797784(v=CS.20).aspx
   5. Start the Group Policy Object Editor or the Group Policy Management Console.
   6. In the Group Policy Object Editor or the Group Policy Management Console, under User Configuration, expand Administrative Templates, expand your version of Microsoft Outlook, expand Outlook Options, and then click the Delegates node.
   7. Under Delegates, double-click Disable shared mail folder caching.
   8. Click Enabled, and then click OK.At this point, the policy setting is applied on your Outlook 2013 client workstations when the Group Policy setting update is replicated. To test this change, at the command prompt, type the following command, and press ENTER:
      gpupdate /force

   After you run this command, start Registry Editor on the client workstation to make sure that the CacheOthersMail registry value exists on the client, and that it has a value of 0:

   Key: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\xx.0\Outlook\Cached Mode
   Name: CacheOthersMail
   Type: DWORD
   Value: 0

   Note The xx.0 placeholder represents your version of Office (16.0 = Office 2016, 15.0 = Office 2013).

   If you see this registry data in the registry, the Group Policy setting was already applied to this client.
   Start Outlook 2013 to verify that this change is implemented.