How to Enable or Disable Cached Exchange Mode?

Gopal Agarwal
5 min readMar 15, 2021

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Microsoft Outlook supports two types of connectivity modes for MS Exchange. You can configure an Exchange account in Outlook to use either Online Mode or Cached Exchange Mode. By default, when a user adds an Exchange account, Cached Exchange Mode with recommended settings is enabled.

What is Cached Exchange Mode?

When Outlook is configured with Cached Exchange Mode, it creates an offline Outlook data file (OST) on the local system storage to store a synchronized copy of mailbox data stored on the server. The feature enables Microsoft Outlook users to have a seamless experience with MS Outlook while accessing their emails even when the system is offline. Thus, problems such as network latency and connection issues do not affect the user experience. Cached Exchange Mode also reduces the load on the mailbox server and network, as Outlook does not require pulling down or uploading information continuously.

Users can continue working offline with Offline Address Book (OAB) and draft emails, which are sent automatically once the system reconnects to the internet

Cached Exchange Mode Settings

Ways to Enable or Disable Cached Exchange Mode in Outlook

Below we have discussed different ways to enable or disable Cached Exchange Mode in various MS Outlook versions.

Enable or Disable Cached Exchange Mode during Account Setup

When you set up an Exchange account in Outlook, the Use Cached Exchange Mode option is already selected by default. To enable the Cached Exchange Mode during account setup, ensure the checkbox is selected.

If you want to disable Cached Exchange Mode, uncheck the Use Cached Exchange Mode checkbox during account setup. This is valid for all Outlook versions.

Enable or Disable Cached Exchange Mode in MS Outlook 2019, 2016, or 2013

Follow the steps to disable or enable Cached Exchange Mode in MS Outlook 2019, 2016, and 2013.

  1. Open MS Outlook, navigate to File > Info > Account Settings and select ‘Account Settings…’ from the drop-down.

2. Select the user account and then click ‘Change.’
4.
In the Change Account dialog box, uncheck ‘Use Cached Exchange Mode’ to disable Cached Exchange Mode or check the checkbox to enable it.
5. Then click ‘Next’ > ‘OK’ and then ‘Finish.
6. After this, restart Outlook to use it in your desired mode.

Enable or Disable Cached Exchange Mode in MS Outlook 2010

The steps to disable or enable Cached Exchange Mode in MS Outlook 2010 are as follows,

  1. Navigate to File > Account Settings, and then click on Account Settings.

2. Navigate to File > Account Settings, and then click on Account Settings.

3. Select or uncheck the Use Cached Exchange Mode checkbox to enable or disable the Cached Exchange Mode (as per your preference).

4. Close and then restart Microsoft Outlook 2010.

What Happens When You Disable Cached Exchange Mode?

You may want to disable Cached Exchange Mode and configure Exchange in Online Mode if your mailbox is large and takes up a lot of storage space on your local system. When you disable the Cached Exchange Mode and restart Outlook, the offline Outlook data file (OST) becomes inaccessible. Thus, you should enable Cached Exchange Mode only after taking a local backup of your mailbox items. Unlike PST, an OST file cannot be imported or accessed from a disconnected or other Outlook profile as it is encrypted by the MAPIEntryID GUID key.

However, if you have forgotten to back up OST data before disabling the Cached Exchange Mode or the OST file turned inaccessible due to large size, you can use an OST to PST converter software, such as Stellar Converter for OST. The software helps you extract mailboxes from the OST file and save them in an Outlook importable PST file.

You may also export the extracted mailbox items, such as emails, attachments, contacts, notes, etc., to an existing Outlook profile, live Exchange, or Office 365 account directly. You may also use the tool to backup mail items from the OST file.

Difference between Outlook Cached Exchange Mode and Online Mode

IMPORTANT NOTE: By default, if a profile is configured in Cached Exchange Mode in Microsoft Outlook and you add another mailbox or shared folder to your profile, then all the folders and mail items that you have access to in the shared mailbox are also stored offline. You may change this behavior and enable caching of only non-email folders, such as contacts, calendars, etc. by creating a CacheOthersMail with DWORD value 0 in one of the following registry keys.

·HKEY_CURRENT_USER\Software\Microsoft\Office<xx.0>\Outlook\Cached Mode
·HKEY_CURRENT_USER\Software\Policies\Microsoft\Office<xx.0>\Outlook\Cached Mode

Conclusion

You may enable or disable Cached Exchange Mode based on your preference or requirements. However, before changing Outlook configuration mode to Online or disabling the Outlook Cached Exchange Mode, you must backup data from the local OST file. This will help save data, which is not synchronized with the mailbox and avoid data loss as the OST file becomes inaccessible. However, if you need to extract mailbox items from an inaccessible or orphaned OST file, an OST to PST converter tool such as Stellar Converter for OST can come in handy. With the help of this tool, you can extract and save mailbox items from an OST file to Outlook importable PST format or export to live Exchange, existing

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Gopal Agarwal

I am a technology enthusiast and loves researching & analyzing new features in Outlook and other popular email tools. https://windtek.org/