Outlook: Demystifying Outlook Cached Mode

Summary:

Outlook 2003 provides a neat feature called Cached Mode. When running Outlook 2003 in Cached Mode, you have the option to download all messages to a local .OST file (similar to a .PST). Thus most of your Outlook tasks is performed locally rather than from your MB that's stored on the server side. This reduces server load and network bandwidth. The following provides list provides an overall picture of running Outlook in Cached Mode.


1. Reduce server load and network bandwidth since tasks/operations are performed locally.

2. You have the option to download all messages when starting Cached Mode or to download only headers such as in IMAP

3. If network connectivity is lost, you still have access to existing content.

4. Some features are still performed on the server side such as Out of Office messages and processing of Outlook rules

5. A common issue user's experience is not getting a real time Global Address List. For example, if a new user is created, a user in Cached Mode may not see this new user in the Global Address Book. This is because when in Cached Mode, you download a copy of the GAL once a day which is by default. You can force to re-download the GAL through Outlook Send\Receive settings. Another option is to use a registry hack

HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\11.0\Outlook\Cached Mode

Value name: ANR Include Online GAL
Value type: REG_DWORD
Value: 1 (1=enabled, 0=disabled)

Additional Resources with GAL and OAB

How to configure how the Offline Address Book is downloaded when you use Outlook 2003 in Cached Exchange Mode
http://support.microsoft.com/kb/823580

Administering the Offline Address Book in Outlook 2003
http://support.microsoft.com/kb/823580

6. Outlook Cached Mode works best with MB's less than 1GB in size.



James Chong
MCSE M+, S+, MCTS, Security+
msexchangetips.blogspot.com


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