How to Split Large OST File into Smaller PST Files Safely?

Summary – Oversized OST files can cause Outlook to slow down, crash, leading to errors and performance issues. To prevent these issues, it’s essential to split OST files into smaller parts. This blog provides complete guidance on how to manage or split oversized OST files using both manual and automated methods. For better performance, data safety, and efficiency, an advanced OST to PST Converter Tool is also discussed for hassle-free results.

Understanding OST Files:

In Microsoft Outlook, an OST (Offline Storage Table) file plays a vital role in storing mailbox data such as emails, contacts, calendars, and tasks locally on your system. These files allow users to work seamlessly even without an internet connection, and any changes made are automatically synchronized once the connection to the Exchange Server is restored.

However, as data accumulates over time, OST files can become oversized, leading to performance issues and errors in Outlook. Understanding when and how to split OST files is essential to ensure smooth functioning and efficient data management.

Issues Caused by Oversized OST Files

When the OST file exceeds its size limit, it can lead to several performance and functionality issues in Outlook, including:

• Slow or degraded performance of the Outlook application.
• Frequent freezing, hanging, or unresponsiveness of Outlook.
• Delays in sending and receiving email messages.
• Synchronization errors between Outlook and the Exchange Server.
• Inability to open or add new data to the OST file.
• Display of frequent error notifications during mailbox operations.

Why Do Users Need to Split or Reduce Large OST Files?

Managing large OST files not only improves Outlook’s performance but also ensures data safety. Here’s why it matters:

• Improves Performance – Keeps Outlook running smoothly and reduces loading times.
• Prevent Corruption – Reduces the chances of data corruption or file damage.
• Avoid Sync Errors – Maintains better connectivity with the Exchange Server.
• Ease of Management – Managing and organizing smaller OST files is simpler and more efficient than dealing with one massive file.
• Free Up Disk Space – Large OST files consume significant storage; splitting them helps optimize system performance and storage utilization.
• Prevent Crashes and Freezes – Keeping OST files within size limits reduces the chances of Outlook freezing or crashing unexpectedly.
• Maintain Compliance – Many organizations enforce mailbox size limits—splitting files ensures adherence to company policies and uninterrupted email flow.
• Simplify Backups – Smaller segmented OST files are easier to organize, faster to back up securely, and restore.

Manual Methods to Fix or Split OST Files

When your Outlook OST file becomes too large, it can lead to slow performance, sync errors, and even corruption. Fortunately, Outlook provides several built-in manual options to manage or split OST files effectively. Below are the most reliable techniques you can try.

Technique 1: Archive Old Emails

Archiving helps move older or less-used emails into a separate PST file, freeing up space in your OST file while keeping your data safe.

• Open Outlook and go to File > Info > Tools > Clean Up Old Items or Archive.
• Choose the mailbox or folder you want to archive.
• Set a date range (e.g., items older than 6 months).
• Select the destination to save the archived PST file and click OK.

Technique 2: Compact the OST File

Compacting helps shrink the size of the OST file by removing unused space. It doesn’t delete any data but optimizes storage.

• Open Outlook > File > Account Settings > Account Settings.
• Under the Data Files tab, select your OST file and click Settings.
• In the opened dialog box, click Compact Now to reduce the file size.

Technique 3: Disable Unnecessary Add-ins

Xtra Add-ins can slow down Outlook’s performance and increase the load time, especially with large OST files.

• Open Outlook and navigate to File > Options > Add-ins.
• Click Manage > COM Add-ins > Go.
• Uncheck unnecessary add-ins and click OK.

Technique 4: Clear Large Attachments and Empty Deleted Items

Emails with large attachments take up a lot of storage. Removing or saving attachments externally helps reclaim space.

• Search for emails with large attachments using the search filters ‘hasattachments: yes’.
• Save important attachments to your local drive.
• Delete the email or attachment after saving.
• Empty the Deleted Items folder by right-clicking it and selecting Empty Folder.

Technique 5: Disable Shared Folder Synchronization

Shared folders increase OST size due to constant syncing. Disabling them can prevent unnecessary data accumulation.

• Go to File > Account Settings > Account Settings.
• Select your account and click Change > More settings > Advanced
• Uncheck Download Shared Folders and click Ok.
• Restart Outlook.

Techniques 6: Use the Outlook Export Option

This method helps you extract essential mailbox data into a PST file, effectively reducing OST file size.

• Go to File > Open & Export > Import/Export.
• Choose Export to a File > Outlook Data File (.pst).
• Select the folders you want to export and set a destination path.
• Click Finish to create a new PST file containing selected data.

Technique 7: Turn Off RSS Feeds

RSS Feeds can add unnecessary data to your OST file. Disabling them helps reduce mailbox clutter.

• Go to File > Account Settings > RSS Feeds.
• Delete or deactivate unwanted RSS subscriptions.

Drawbacks of Manual Methods:

While manual solutions are free and effective for small-scale maintenance, they come with certain limitations:

• Archived or shared data may not be available offline.
• Requires repeated manual effort–no automation for ongoing management.
• Not suitable for large, severely corrupted, or complex OST files.
• Provides limited space reduction and performance improvement.
• Risk of accidental data loss or missing attachments during the process.
• Time-consuming and requires technical knowledge to execute correctly.

Manual approaches work for moderate-sized OST files but may not fully resolve performance issues or prevent future file bloat.

Split Large OST File Using a Professional Method

The Shoviv OST to PST Converter Tool offers a fast, reliable, and secure solution for managing large OST files with ease. Trusted by IT administrators and Outlook users alike, this professional utility is known for its accuracy, speed, and user-friendly design. It allows users to efficiently split oversized OST files into smaller PST files based on various criteria such as size, date, folder, or sender, ensuring smoother management and storage.

Thoughout the conversion or splitting process, the tool preserves data integrity, guaranteeing that no information is lost or corrupted. Its intuitive interface makes it suitable for both beginners and experienced professionals, while its wide compatibility ensures support for OST files from all versions of Outlook, including 2021, 2019, 2016, and earlier editions. Additionally, the advanced preview option enables users to view their mailbox data before conversion, ensuring complete accuracy and control over the process.

Steps to Convert or Split OST Files Using Shoviv Software:

• Download and open the Shoviv OST to PST Converter on your system.
• Click the Add OST File button on the ribbon bar, then browse or search for the required OST files and click OK.
• Once added, the tool displays all mailbox items—review and select the required data for conversion or splitting.
• Select Save All Files in Outlook PST as the output format. You can choose to export data to an existing PST or create a new one.
• Use the Process Message Class and Process Item Date filters to include or exclude specific items.
• Enable the Split PST option and set a desired size limit to divide large OST files into smaller, more manageable PSTs.
• Click Next to begin the process. Once completed, you can save the detailed report for future reference.

Also Read: How to Split a Large PST file into Smaller Parts?

Conclusion:

In this blog, we explored the reasons behind oversized OST files and several methods to handle them. Although manual techniques can help reduce OST size to some extent, they have limitations and may not completely prevent future issues.

For a more secure and efficient approach, using a professional tool like Shoviv OST to PST Converter is highly recommended. It automates the splitting process, eliminates data loss risks, and ensures smooth Outlook performance without any technical hassle.

Frequently Asked Questions: