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Summary: The blog discusses OST files in Outlook, focusing on offline access and synchronization. It addresses errors and introduces Kernel for OST to PST Converter as a reliable solution for data recovery and conversion, while emphasizing OST-PST distinctions for mailbox management.

Within the realm of corporate dynamics, communication, particularly via email, is a bustling domain. Outlook stands out as a prominent tool for email correspondence, extensively embraced across the business landscape. It seamlessly integrates with Exchange Server and webmail services. When operating in offline mode within Outlook, a localized duplicate of your mailbox materializes on your system, encompassing essential elements such as email messages, calendar events, and other pertinent items. This localized duplicate, recognized as an Offline Outlook Data (.ost) file, plays a pivotal role in facilitating offline access to your mailbox content.

Users have the ability to access the downloaded or synchronized email messages, calendar events, contacts, and tasks without the need for an active email server connection. This means they can compose new messages, add contacts, and create appointments, although they won’t be able to send or receive new messages until they’re back online.

When the connection to the email server is reestablished, any changes made to the Offline Outlook Data (.ost) file will automatically synchronize with the mail server, ensuring that all updates are reflected consistently. It’s worth noting that various email account types, including Outlook 365, IMAP, Exchange, and more, maintain synchronized copies of mailbox information in these Offline Outlook Data (OST) files, providing users with seamless access to their data across multiple accounts.

To know more details about what is OST file, read this blog carefully and get the comprehensive and authentic information.

What is an OST File? Brief Definition

Fundamentally, “OST” abbreviates to “Offline Outlook Data File” or “Outlook Offline Storage Table.” Within an OST file, various data types, including calendars, journals, and schedules, are meticulously organized to enable offline accessibility. OST files, in essence, are renowned for their role in storing data for offline use within Outlook.

It generates a localized copy either in Cached Exchange Mode or operates in offline mode, preserving a local replica of the data. When the connection is reestablished, the OST file undergoes synchronization with the server, as these offline folders mirror the folders present in the server mailbox. This entire process is referred to as folder synchronization.

How to look for Outlook OST file?
  1. Go to Outlook; select the File tab.Outlook
  2. A window will appear here; select Account Settings; click Account Settings.Account Settings
  3. Now, in the Account Settings window, click the Data Files files
  4. Now, select an .ost file and click Open Folder Location.Open Folder Location
  5. After selecting Open File Location, a window with the file location will appear.file location
Common Errors with the Outlook OST File

Now that we have a clear understanding of what an OST file is, it’s important to note that users may occasionally encounter errors when working with Outlook OST files. These errors can stem from various causes, and we’ll explore some of them here.

  • Orphaned or Corrupt OST file
    Orphaned and corrupted OST files are typically encountered when there is no corresponding mailbox available on the server. Several factors can contribute to the corruption of OST files, including hardware problems, power outages, or system bugs. Here are some error messages commonly associated with OST file issues:
  • (0x800CCC0F) Sending / Receiving reported error.
  • Cannot start Microsoft Outlook.
  • (0x8004010F) OST file cannot be accessed.
Methods to Recover Orphaned and Corrupt OST files
Delete OST File and Re-create it

If you find yourself unable to access your OST file, you can consider the following solution. First, locate and delete the OST file from its directory. Afterward, Outlook will automatically initiate the process of downloading mailbox data from the mail server to recreate the OST file.

  1. Open Outlook, find the OST file location
  2. Delete the OST file from its location.
Create New Outlook Profile

Before creating a new Outlook profile, it’s essential to close the Outlook application. If you decide to recreate the OST file using an existing OST file, always ensure that you have a backup copy of that file in the new location to prevent data loss.

  1. Go to Control Panel and click on the Mail option.
  2. A new window will appear; here, go for the Show Profiles option.
  3. Now click the Add option in the appeared window.
  4. Now, a New Profile window will appear; here, type the name and tab on the Next button.
  5. After completing the above procedure, go for the Change Account settings option and click the Next option again.
  6. Select the More Settings option in the Server Settings box.
  7. Click the Advanced option from the above menu and select Outlook Data File Settings.
  8. Next, to save this new OST file, go to the Browse option to change the OST file location. Finally, click on the OK button.
  9. If you wish to utilize your existing OST file, simply browse to the location of the copied file, select it, and then click on the “Open” button.
Use Kernel for OST to PST Converter

Frequently, users approach us with inquiries about the effectiveness of manual methods in resolving OST-related issues. In response to these concerns, our experts have developed an OST to PST Converter designed to address the complexities of manual procedures. This tool swiftly and seamlessly recovers all OST items, including emails, attachments, contacts, distribution lists, calendars, tasks, and notes, and stores them in PST format. Additionally, it offers the capability to convert OST emails into various other formats such as PST, DBX, MSG, EML, TXT, RTF, HTML, MHTML, and PDF. It functions seamlessly with all versions of MS Outlook.

It’s important to note that OST and PST files, while seemingly similar, exhibit significant differences. They can be likened to two sides of the same coin, each serving distinct purposes and characteristics within the Outlook environment.


I trust you have found this blog informative in gaining a better understanding of what an OST file is. These files are immensely valuable when users need to access their email, appointment calendar, and other data offline without requiring a server connection. However, disruptions can occur due to OST errors, and manual solutions may not always prove effective. To address these issues, users can turn to Kernel for OST to PST Converter, a reliable solution for converting OST files to PST format and ensuring seamless access to their mailbox data.

Kernel for OST to PST