What is Cached Exchange Mode in Outlook?

Aftab Alam
Aftab Alam linkedin | Updated On - December 30, 2022 |

Read time 5 minutes

Cached Exchange Mode is one of the two modes to connect the Outlook application with an Exchange Server. The other one is Online Mode. The Cached mode has the job of keeping a local copy of the user’s Exchange mailbox stored on the hard drive in the form of an OST file. While the Cached mode is enabled in Outlook, the Outlook client will check the OST file for all the information and constantly update the mail and synchronize it to open the cached file.

The Cached Exchange Mode Provides the Following Benefits to the User –

  1. Apart from a primary mailbox, the Cached mode also keeps a copy of the Offline Global Address Book (GAL).
  2. A user can make changes in the mailbox, like accessing emails and saving drafts even when the Internet is down.
  3. It is useful for high latency connections.
  4. Searching files and information is quite easy in offline storage (OST) files.
  5. In satellite and radio-frequency-based connections, the OST file works much better than the online files.
Instant Solution

Try automated tool Kernel for OST to PST to access the content from an inaccessible OST file.

Difference between Cached Exchange Mode and Online Mode –
  1. Cached Exchange Mode requires a lot of disk space in comparison to Online Mode.
  2. The number of features in Cached Exchange Mode and Online Mode is different.
  3. An index can be prepared by searching content locally in Cached mode.
  4. In Cached Exchange Mode, you cannot perform searching in emails.
Issues You May Face While Working in Cached Exchange Mode

Cached mode is beneficial when you want to work offline. But while working in the cached mode, multiple issues can occur with Outlook.

Here are some examples:

  • Some of the messages may be stored only in the OST file and will not be available in the Exchange mailbox.
  • Some important information like calendar items will point to the local files rather than the Server files; so it is difficult to share the calendar entries in the cached mode
  • If you enable the cached mode to an existing mailbox that already has a large amount of data, that may create downloading issues.
  • The response time for the identification of the corruption issue in the mailbox may take more time.
  • If the OST file that has been created after enabling the Exchange Mode becomes corrupt, then all its data will be lost before connecting with the Exchange Server. Also, if the OST file gets disassociated with the account, all information saved will be lost.
How can I Access the Content From an Inaccessible OST File?

A user cannot open an inaccessible or corrupt OST file. Although the ScanPST tool can check for corruption in the OST file, it is not suitable to retrieve data from inaccessible OST files. In such cases, you need to assistance of professional software. Kernel for OST to PST Converter is specialized software for restoring data from OST files. It can recover the data, provide the preview, filter the recovered data, and save it in multiple formats, including the PST file.

How to turn on Cached Exchange Mode in Microsoft Outlook application?

Cached Exchange Mode is perfectly suitable for Exchange Server users. It saves a local copy of your online mailbox to your computer. Follow the simple procedure here –

  1. Follow File>>Account Settings>>Account Settings.
  2. Account Settings

  3. Select the Exchange Account and click Change.
  4. Change Exchange Account

  5. In the Offline Settings, check Use Cached Exchange Mode.
  6. Restart the Outlook application again.
Enable Cached mode in Outlook 2010

The user can turn on the cached mode in Outlook 2010 using the following steps-

  1. Click File in the top menu bar.
  2. Follow Account Settings >> Account Settings.
  3. Select the Exchange account from the account list in the Email tab and click Change.
  4. Go to the Microsoft Exchange Server field, and below the name of the Exchange, use the checkbox to select ‘Use Cached Exchange Mode.’

In the Cached Exchange Mode, users get the Download preferences to download mailbox data in different situations.

  1. Follow Send/Receive >> Preferences >> Download Preferences.
  2. Choose amongst the given options – Download Full Items, Download Header and then Full Items, Download Headers, On Slow Connections Download Headers Only.
How to turn off Cached Exchange Mode in Microsoft Outlook application?

If you want to turn off the Cached Exchange Mode follow the above-given method and uncheck the Use Cached Exchange Mode.

There is no Cached Exchange Mode in my Microsoft Outlook application –

If there is no Cached Exchange Mode option in your Outlook application, then there can be the following reasons behind this scenario –

  1. Microsoft Outlook does not have an Exchange Account –
    If there is no Exchange Account included in Microsoft Outlook, there will be no option of Cached Exchange Mode. POP3 and IMAP accounts do not have this feature.
  2. Exchange server administrator has disabled this feature –
    An Exchange Server administrator can easily disable the feature of Cached Exchange Mode.
  3. Microsoft terminal service is installed –
    If the windows computer has a Microsoft terminal installed in it, then cached Exchange Mode will not be available also.
How can I verify that Cached Exchange Mode is enabled?

Verifying the status of Cached Exchange Mode is quite easy to check. Look at the bottom of the right-hand side of the Outlook application, it should say Connected to Microsoft Exchange, and an OST file is present in the computer. It means that the Cached Exchange Mode is enabled.
If Cached Exchange Mode is not enabled, then it will say Online with Microsoft Exchange.

How can I access the content from an inaccessible OST file?

A user cannot open an inaccessible file in the Outlook application. If you want to recover the content of an OST file, then you should use a professional tool like Kernel for OST to PST which can recover complete OST file data. OST to PST converter is one such tool that can recover a severely corrupt OST file by converting it into PST format accessible in Outlook.


Cached Exchange Mode in Outlook is a very useful feature as it facilitates the user’s exchange box in the offline mode. This article discusses all about the Cached Exchange Mode, from its benefits to errors, from enabling to disabling it. There lies a major difference between Cached Exchange Mode and Online Mode in Outlook which has been discussed above. One issue faced by Outlook users is OST file corruption and it has the ability to make the file inaccessible. You can try some manual fixes to repair OST files but choosing Kernel for OST to PST Converter which a professional software will be better.

Kernel for OST to PST