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. 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

   Note The .adml file must be copied from the correct language folder.

5. Start the Group Policy Object Editor or the Group Policy Management Console.Note Because you may be applying the policy setting to an organizational unit and not to the whole domain, the steps may also vary in this aspect of applying a policy setting. Therefore, check your Windows documentation for more information.
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.Screenshot for Outlook 2016:
   

   Screenshot for Outlook 2013:

   
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:

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. .

Outlook 2010

The default Group Policy template (Outlk14.adm) for Outlook 2010 does not contain the policy setting that controls this functionality. Therefore, you must use a custom Group Policy template to manage this functionality.

To deploy this setting by using a custom Group Policy template, follow these steps:

1. Download the following file from the Microsoft Download Center:
   http://download.microsoft.com/download/2/1/F/21FB30E6-C526-4B65-BAF1-7FE0E2252879/outlk14-DisableCachingSharedMailFolders.zip

   Note The custom .adm template contains the following text.

   CLASS USER
   
      CATEGORY !!L_MicrosoftOfficeOutlookCachedSharedMailFolders
            POLICY !!L_TurnOnOffSharedMailFolderCaching
                KEYNAME "Software\Policies\Microsoft\Office\14.0\Outlook\Cached Mode"
                EXPLAIN !!L_TurnOnOffSharedMailFolderCachingExplain
                VALUENAME "CacheOthersMail"
                VALUEON NUMERIC 0
                VALUEOFF NUMERIC 1
            END POLICY
         END CATEGORY
   [strings]
   L_MicrosoftOfficeOutlookCachedSharedMailFolders="Outlook 2010 Shared Mail Folder Caching"
   L_TurnOnOffSharedMailFolderCaching="Disable shared mail folder caching"
   L_TurnOnOffSharedMailFolderCachingExplain="This policy controls the caching of shared mail folders in Outlook 2010 \n \n By default, Outlook 2010 caches shared mail and non-mail (Calendar, Contacts, Tasks) to which you have access.\n \n Enable this policy to configure Outlook to only cache shared non-mail folders. This mirrors the default shared folder caching behavior in Outlook 2007.\n \n If you disable this policy or do not configure this policy, shared mail and non-mail folders to which you have access are cached in your .ost file when you add another mailbox to your profile."
   
   
   
   

2. Add the Outlk14-DisableCachingSharedMailFolders.adm file to the Group Policy Object Editor or to the Group Policy Management Console.Note The steps to add the .adm file to the Group Policy Object Editor or the Group Policy Management Console vary, depending on the version of Windows that you are running. Also, because you may be applying the policy setting to an organizational unit and not to the whole domain, the steps may also vary in this aspect of applying a policy setting. Therefore, check your Windows documentation for more information.Go to step 3 after you add the .adm template to the Group Policy Object Editor or to the Group Policy Management Console.
3. In the Group Policy Object Editor or the Group Policy Management Console, under User Configuration, expand Classic Administrative Templates (ADM) to locate the policy node for your custom template. By using the custom *.adm template that is provided in step 1, this node is named Outlook 2010 Shared Mail Folder Caching.
   
4. Under Outlook 2010 Shared Mail Folder Caching, double-click Disable shared mail folder caching.
5. Click Enabled, and then click OK.At this point, the policy setting is applied on your Outlook 2010 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:

If you see this registry data in the registry, the Group Policy setting was already applied to this client. Start Outlook 2010 to verify that this change is implemented.