How to Change Outlook Offline File into Another Format

Reasons to Change Outlook Offline File into Another Format

An OST file is tied to the profile created by MS Outlook. If the Outlook profile is deleted, accessing the mailbox data becomes difficult.

Converting the file into another format allows users to store, migrate, or access their emails without creating a new Outlook profile.

Situations where you usually need to change Outlook Offline File into Another Format:

• If MS Outlook isn't opening on your system, or your Outlook profile was accidentally deleted.
• You have a new profile and want your previous Outlook file to sync with it, or you want to migrate it to a new system.
• For a long-term backup of important email data, you need to change the file format to .pst or another format, since OST files cannot be backed up directly.

Effective Methods to Change Outlook Offline File into Another Format

There are three main solutions for converting OST files. The method you choose depends on how effectively and safely you want your important email data restored.

The 3 listed methods are:

1. Import/Export using MS Outlook (not available for Outlook Web)
2. Reconnecting the syncing profile in MS Outlook
3. Advanced Professional Solution for direct file conversion

Manual solutions work only under specific technical conditions, whereas automated methods are independent of such constraints.

Manual Method 1: Import/Export using MS Outlook

This is a built-in feature of MS Outlook and works only when the Outlook profile is active and mailbox data is accessible in the desktop version.

Steps to follow:

1. Open Classic MS Outlook (Desktop version).
2. Click File > Open & Export.
3. Select Import/Export.
4. Choose Export and click Next.
5. Select Outlook Data File format.
6. Choose either folder or the whole mailbox to export.
7. Browse to the destination path and click Finish.

MS Outlook will create a new folder in the selected file format, which can now be moved or accessed independently. This method is not supported in Outlook Web or the New Outlook version.

Pros of this method:

• Built-in feature in Classic Outlook
• Simple steps to export
• Option to select folder or entire mailbox
• Maintains folder hierarchy and attachments
• Suitable for smaller mailboxes

Manual Method 2: Reconnecting the Profile with MS Outlook

When the offline file becomes inaccessible or there are syncing issues, reconnecting the profile can restore mailbox access.

This method rebuilds the connection between Outlook and the server. Once synchronization is restored, users can export mailbox data into another format for safer, long-term backups.

Steps to follow:

1. Close MS Outlook completely.
2. Open Control Panel > Mail.
3. Select Show Profiles and view profiles.
4. Remove the profile and re-add it.
5. Enter account credentials and complete setup.
6. Launch Outlook with the same profile.

Outlook will re-sync mailbox data and generate a new offline file automatically. You can also rename the existing data file to force Outlook to create a fresh offline file. This method works only when mailbox data exists on Exchange, IMAP, or Office 365 servers.

Pros of this method:

• Restores mailbox data when syncing fails
• Rebuilds a fresh offline file from the server
• Maintains original mailbox structure and folder hierarchy
• Resolves minor corruption or profile errors
• Newly created data files can then be converted into another format
• Renaming the data file is quicker than reconnecting the entire profile

Drawbacks of Manual Methods

Manual OST conversion has limitations. These methods depend on server connectivity, profile configuration, or mailbox accessibility. Large, corrupted, or orphaned offline files may not convert reliably.

• Requires active server connection
• Does not work for orphaned or disconnected OST files
• Cannot handle corrupted or deleted profiles
• Time-consuming for large mailboxes or multiple folders
• High risk of incomplete data export, especially with attachments
• Version-specific restrictions in MS Outlook

Due to these limitations, manual methods are not recommended for complex scenarios. A professional solution is more efficient for bulk or risky conversions.

Professional Method for Changing Outlook Offline File Format

When manual methods fail, it is essential to convert OST to PST. This tool handles large, corrupted, orphaned, or inaccessible OST files efficiently.

Steps to use the professional tool:

1. Install & launch SysTools OST Converter.
2. Click Add File and select your offline Outlook file.
3. Choose either Export All or Export Selected items.
4. Select the desired output format, such as PST.
5. Click Export and wait for completion.

You can open the exported PST in MS Outlook to verify the conversion.

Benefits of Using the Advanced Solution

• Works without internet connection, Outlook profile, or server connection
• Recovers data from damaged or orphaned OST files
• Preserves folder structure, attachments, and mailbox data
• Saves significant time compared to manual methods
• Supports multiple export formats for migration or long-term backup

This ensures mailbox data remains accessible, organized, and safe for future use.

Final Verdict

Converting Outlook offline files is crucial when mailbox access is lost, profiles are deleted, or data needs migration or backup. Manual methods work in limited scenarios but are time-consuming and dependent on server connectivity. A professional solution provides a reliable, efficient, and secure way to convert files, preserving emails, attachments, and folder structures for long-term accessibility.