Convert OST to PST

Compatibility: Outlook for Microsoft 365, Outlook 2021, Outlook 2019, Outlook 2016, Outlook 2013, Outlook 2010, Outlook 2007

OST to PST Converter is a powerful tool that can convert multiple OST files to PST files. The tool can extract emails from .ost files without requiring Microsoft Outlook or a server account connection. This makes it a useful application in case of data loss, corruption, or inaccessibility of .ost files. However, Microsoft Outlook must be installed on your PC to create a new .pst file or exporting to an existing .pst file.

Export or backup email, contacts, and calendar to an Outlook .pst file

When you can open an .ost file in Microsoft Outlook, you can use it to export items by creating a .pst file. However, if you're using Cached Exchange Mode, Outlook will only export the items in your current cache. By default, Outlook configures Exchange and Microsoft 365 accounts to only synchronize the past 12 months of your email. Follow the export instructions to move your email from the .ost file to a .pst file. To export more than the past 12 months of data, turn off Cached Exchange Mode first.

If you encounter Outlook connection issues or cannot open your .ost file, use OST PST Viewer to open, export or backup emails from your .ost file.

Convert OST to PST

After your email data is exported to a .pst file, it's portable. You can save, backup, or open the converted .pst files on another computer. Follow these steps to convert one or multiple OST files to PST files.

  1. Close Microsoft Outlook and all other mail-enabled applications that may use your Outlook mailbox.
  2. Download the OST to PST Converter, and run it on your computer.
  3. Browse the OST file or folder with OST files you want to convert and click Open.
  4. Select the target path for converted PST files.
    OST to PST Converter
  5. Setup export parameters and click Run
  6. Wait for the export to complete.
    OST to PST Converter Report
  7. Once finished, review the summary and log information for any issues or errors.

Customize Your OST to PST Conversion

The OST to PST Converter offers a range of export options to customize your conversion. Choose to create separate folders for each OST file, preserve the original folder structure, ignore empty folders, create separate PST files for each folder, and automatically rename converted files if necessary.

Find and Export specific selected items to PST files

Follow these steps to find and export specific selected items from OST to PST files:

  1. Close Microsoft Outlook and all other mail-enabled applications that may use your Outlook mailbox.
  2. Download the PST OST Viewer, and run it on your computer.
  3. Browse the OST file you want to convert and click Open.
  4. Preview all your items including email messages, calendar, contact, and task data..
    OST PST Viewer
  5. Select specific items and go to File > Export.
  6. Choose PST - Outlook Data File as file format and Selected items only.
    Convert emails from PST to EML files
  7. Select destination folder and click Ok.
  8. Wait for the export to finish and click Ok.

What data is exported?

  • When OST to PST Converter exports email, contacts, and calendar info to a .pst, it makes a copy of the information. Nothing leaves .ost file. You'll still see and have access to your email, contacts, and calendar in .ost file.
  • When tool exports emails, it includes any attachments to the emails.
  • OST to PST Converter does not export meta-data such as folder properties (views, permissions, and AutoArchive settings), message rules, and blocked senders lists.

Online services to convert OST to PST

OST files contain your important and confidential data. When you use an online service to convert email from OST to PST, all of your sensitive data, including private messages, contacts, tasks and notes, is transferred to someone else's server. The data is processed on an unknown computer and you have no control over it. Only then will you be able to download the resulting PST file.

Unlike online converters, our utility works strictly on your computer. Information from the OST data file is not uploaded anywhere. Your data will not fall into the wrong hands.

Are there any limits when converting from OST to PST?

There is no limit on the number and size of the converted OST files and the resulting PST files. You can convert unlimited files as often as you like.

–°onverting OST to PST using Powershell

The program can bulk convert PST to OST in batch scripts using PowerShell, Task Scheduler and other automation tools. To do this, use the command line options of the product.

Note: Command line parameters are not available in the Home license.

   [-HardDeleted | -HardDeletedOnly]


The filename parameter specifies the .pst and .ost files to process. A filename mask can be applied, e.g. c:\users\*.pst

The E parameter specifies the file format for the saved messages. Exports to a file of the specified format:
  • msg - .msg file format
  • umsg - unicode .msg file format
  • eml - .eml(rfc 822) file format
  • pst - .pst Outlook Data File
  • mbox - .mbox Mozilla Thunderbird file format
The Name parameter specifies the naming style for the saved messages:
  • Id - incremental Id
  • EntryId - PR_ENTRYID (unique message identifier)
  • Subject - message subject
Specifies search query, see search keywords and boolean search operators

Specifies destination folder for bulk extracted messages

Extensive scan (to recover data from a damaged or a corrupted .pst, .ost files)

Find 'hard deleted' and 'orphaned' items

Export only 'hard deleted' and 'orphaned' items

Create .log file in ExportPath folder


Example 1

cd "C:\Program Files (x86)\PST Walker\"
$PSTFiles = @("c:\a.ost", "c:\b.ost") foreach ($PST in $PSTFiles){ .\pstwalker-cli.exe "$PST" --% -E:pst -SearchQuery:'from:( OR "bobby moore")'-ExportPath:"D:\PST-Exports\" }

This example searches c:\a.ost and c:\b.ost mailboxes for items in which the e-mail address equals OR sender name contains bobby moore. The search results are exported to D:\PST-Exports\a.pst and D:\PST-Exports\b.pst

When running native commands from PowerShell, the arguments are first parsed by PowerShell. Beginning in PowerShell 3.0, you can use the stop-parsing (--%) token to stop PowerShell from interpreting input as PowerShell commands or expressions.

Example 2

Command Prompt
cd C:\Program Files (x86)\PST Walker\
pstwalker-cli.exe c:\users\*.pst -E:eml -ExportPath:"D:\PST-Queries\" -SearchQuery:'subject:"Your bank statement"' -FullScan -HardDeleted

This example searches all .pst files in c:\users folder for messages and hard deleted messages that contain the phrase "Your bank statement" in the subject. The search results are exported as .eml files to D:\PST-Queries\.

Updated on May 23, 2023

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See Also

Recover deleted folder and emails in Outlook

Accidentally and permanently deleted items in Outlook? Stop using Outlook immediately, download a recovery tool, open your mailbox in safe mode, and follow the tool's instructions to recover your deleted items.

Recovering emails from an OST file

There are several tools available that can help you recover data from an OST file. They can help you recover important data from your OST file and save it in various file formats for future use.