Read time: 7 minutes

Summary: Outlook, a Microsoft Office component, supports email and productivity. Cached Exchange Mode syncs mail folders but can encounter issues. Solutions involve manual updates, sync settings, PST archiving, add-in removal, and profile recreation.

Outlook stands as the premier email management service, serving as an integral component within the Microsoft Office suite. It offers a comprehensive suite of tools encompassing email, calendar, contact, and task management, streamlining the workflow for professionals across various domains. Outlook operates in two primary modes, namely Online and Cached Exchange, when establishing connections with the Exchange server. The Cached Exchange Mode in Outlook keeps a local copy of the user’s mailbox data and stores it in an OST file. The changes made here are updated in the mail folder continuously.

When these updates fail to occur, it can lead to significant issues for the user. Occasionally, the system may display the correct last synchronization time, yet fail to reflect new emails in the Inbox. The underlying causes of this problem can vary, but the available solutions are somewhat limited. In this discussion, we delve into these solutions in detail.

Causes of mail folder issues in cached mode

  • Disabled auto sync facility
  • Network connectivity issues
  • Oversized OST file
  • Incompatible add-ins in Outlook
  • Corruption in the current profile
  • Interruptions by antivirus program
Solutions to fix ‘Outlook is not updating mail folders in cached mode’

These are all the solutions that will help you to deal with OST synchronization issues with Exchange Server while working in the cached mode:

Update folders manually

For reasons that may not always be immediately apparent, the data updating process may occasionally malfunction. To gain a better understanding and potentially identify any other contributing factors behind the issue, you can manually initiate the data update.

  1. Launch MS Outlook and move to the Send/Receive tab.
  2. Click on the Update Folder option and check if the problem still exists.Update Folder
Turn on the ‘Send immediately when connected’ option

Before exploring alternative solutions, it’s important to verify that the ‘Send immediately when connected’ feature is enabled when accessing your Exchange server account. Enabling this option ensures continuous synchronization and can help resolve the issue.

  1. Click File > Options from the left panel.File and Options
  2. Now, select the Advanced option. Scroll down to the Send and receive section and check Send immediately when connected. Finally, click on on OK
Reset the sync slider

The sync slider serves to restrict the quantity of data stored offline within OST files, preventing them from becoming excessively large. The file size is determined by the number of days you specify.

  1. Open Outlook and click on the File tab. Select Account Settings under the same option.Select Account Settings
  2. Double-click on the required email address.
  3. Under Mail Settings, adjust the slider based on your requirement, and click Next
  4. Save the necessary changes and restart Outlook.
Move older emails to a PST file

An excessively large and burdened OST file can lead to unexpected issues. It’s advisable to archive your older emails by transferring them to a PST file. This secure format ensures convenient access to your files whenever necessary.

  1. Select the File tab. From the Mailbox settings, choose Clean Up Old the file tab
  2. Choose the date and folder which you want to move. Click on Browse to select the destination. Click on OK.Click on OK

A major drawback is that one will have to repeat the process for each folder every time. However, a better approach is to opt for professional software like the Kernel for OST to PST Converter, which manages all your valuable data with utmost integrity and security. In addition, it provides various other choices of format to save your data.

Remove incompatible Add-ins

Occasionally, certain add-ins may not be fully compatible with the Outlook program, leading to concurrent issues. In such cases, it’s advisable to uninstall these add-ins to ensure uninterrupted, error-free work.

  1. Select the File tab and click on Options.
  2. From the new window, select Add-ins.
  3. The complete list of all the add-ins will appear. Select go
  4. Now, uncheck all of them and click on on OK
  5. Restart Outlook and enable one add-in at a time to find the faulty one. Eventually, you can remove it permanently.
Set up a new Outlook profile

A corrupted profile can also be a culprit behind delays in updating mail folders in Cached mode. To mitigate this issue, consider creating a new Outlook profile and configuring your email settings afresh

  1. In Control Panel in your system and select Mail.
  2. The Mail Setup window will open. Here, select Show Show Profiles
  3. Click on Add to create a new Profile. Enter all the required credentials.Click on Add
  4. Launch Outlook and select the New Profile prompt. It will start synchronizing all the items.


When Outlook is not updating mail folders in Cached mode, it halts an individual’s communication. It can be risky for the overall functionality of the organization. And recently, many users have complained about facing synchronization issues with the Exchange mailbox. To address this issue effectively, start by enabling the ‘Send immediately when connected’ option in your Exchange account settings. Another common culprit is an oversized OST file. You can tackle this problem by archiving older emails to a PST file and adjusting the sync slider to a more suitable setting. When transferring the contents of OST files to PST, consider using specialized software like Kernel for OST to PST Converter, designed for this purpose. If none of these solutions prove successful, you may want to create a new Outlook profile and configure your email account from scratch.

Kernel for OST to PST