Most users, especially those will laptops, will want Outlook to operate in Cached mode but you likely don’t want Outlook caching on boardroom / focus room / huddle room / client room computers. Cache mode copies a large amount of data from the Exchange server to an .OST file on local PC and in a boardroom that:

1. takes a few minutes users seldom have in a meeting
2. opens a security hole by putting potentially sensitive email on another computer
3. take up considerable space, especially if you have hundreds of users

So what you need to do is leave Outlook’s default settings of caching 1 year of mail on the users primary computer but block Outlook caching on shared computers like boardrooms. The problem is that Outlooks cached mode settings in HKey_Current_User (HKCU) and you need to apply it only to some computers.

To this, you simple need to set ITEM LEVEL TARGETING. Unfortunately most GPO’s do not have ITEM LEVEL TARGETING as an option and that includes CACHED EXCHANGE MODE GPO. Fortunately registry changes do and so all you have to figure out is what registry change you need to make. We have the answer:

Enable or disable Exchange cached mode in Outlook. Open the Account Settings dialog box. In Outlook 2010 and 2013, please click File Info Account Settings Account Settings. Cached Exchange Mode is one of the two modes to connect the Outlook application with an Exchange account. The other one is Online Mode.The cached mode has a job of keeping a local copy of the user’s exchange mailbox stored on the hard drive in the form of an OST file.

1. Create new or edit an existing GPO
2. Expand USER CONFIGURATION > PREFERENCES > WINDOWS SETTINGS > REGISTRY
3. Right click and CREATE NEW
4. Set SoftwarePoliciesMicrosoftOffice16.0outlookost VALUE=NoOST REG_DWORD=2
5. Click the COMMON > ITEM-LEVEL TARGETING > TARGETING… (button)
6. Click NEW and add the condition you want. In the screen shots below I set it any computer in the OU = KIOSKS

• How to Disable Cached Mode in Outlook. Exchange mail accounts by default use cached exchange mode, which makes Outlook store your recent messages and contacts on your computer for easier access.
• The Outlook cached mode slider, managed by Group Policy. The Outlook cached mode slider does not directly control the size of your OST file in gigabytes. Instead it allows you to select how much data is downloaded from your mailbox by age. The slider’s default setting depends on size of the hard disk in your computer.

Outlook Cached Mode Vs Online Mode

Click on these screen shots to enlarge them