• Clear Outlook Cache Files Using File Explorer. Using File Explorer to clear Outlook cache is one of the easiest ways to do the task. Since cache files are like any other regular files on your computer, you can navigate to the folder where they’re located and get rid of all of them at once.
• You can force Outlook on a single computer to use cached or online mode without creating a group policy by setting this registry value: HKEYCURRENTUSER Software Microsoft Office xx.0 Outlook Cached Mode. Where xx.0 is 14.0 for Outlook 2010 and 15.0 for Outlook 2013. Set this value to 1 to force cached mode or 0 to force online mode.

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:

No, Administrator permissions did not allow me to turn off cached exchange mode. The regedit instructions above were fine, except that there is no OST key entry for Office 16 (365 subscription). I have to change data files since I don’t use hotmail calendar or contacts.

How To Turn Off Cache Mode In Outlook For Mac

Outlook 2016 Cache Settings

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

Click on these screen shots to enlarge them