How to Convert OST to PST

Posted on by Marho Atumu | Updated:
Reading Time: 5 minutes

A key email client feature is accessing your emails when you do not have an active Internet connection. Microsoft’s Outlook email client downloads and saves information from your online email account locally on your computer. These email files are saved primarily in two file formats, but what are they? Let’s find out!

What are Outlook Data Files?

Outlook uses both Offline Storage Table (OST) and Personal Storage Table (PST) data files but decides which to use based on the connected email’s protocols and accounts:

  • OST: Used for Internet Message Access Protocol (IMAP) accounts, exchange accounts, and those from Microsoft 365. These account types usually store a copy of messages locally without deleting them from the online email service. The email client will synchronize any changes you make to mail items locally with the online email service.
  • PST: Used for Post Office Protocol (POP) email accounts. These email accounts typically download all email messages from the email service and then delete them from the online service, making them only available locally on the computer where the email client downloaded them. Outlook also uses PST for backups and exports of all kinds of email accounts.

Why Convert OST to PST?

One popular reason you may need to convert an OST file to PST is to backup your messages. PST data files can be transferred from one system to another and easily re-imported in another email client, giving you access to all the mailbox items. Moving mailbox items between systems like this isn’t possible if they are stored in OST data files.

Liquid Web's Premium Business Email syncs easily with Personal Storage Table data files.

You could choose to create another OST data file for a linked email address which will require re-downloading all the contents of your email account, but this is less than ideal, especially if you have a large mailbox. Also, suppose you happen to be in a situation where you no longer have access to the online email account associated with an OST data file. In that case, you’re out of luck as you can’t copy the OST file to another computer. Your only option would be to convert it to a PST data file.

OST to PST Conversion

We will look at two of the more popular ways to convert OST files to PST without the need for additional software tools.

Export OST to PST

The most straightforward way to convert an OST file to PST is from the Outlook email client itself. The steps outlined below are for Microsoft Outlook 2016 onwards and the version of Outlook that comes with Microsoft Office 365. There may be some variation when it comes to the older versions of the program.

1. Launch the Microsoft Outlook email client, and click on the File menu item at the top left of your screen. From the list of options that appear, select Open & Export and then Import/Export.


2. The Import/Export Wizard will open in a new dialog box. From the list of actions to perform, select Export to a File and click the Next button.


3. Select Outlook Data File (.pst) from the options on the next page of the Wizard, and then click Next.


4. Select which folders from the email account you want to export to the newly created .pst file. You can also choose to backup the entire email account by selecting it instead of the individual subfolders.


5. Click the Browse button to choose the file location where to save the exported file and set the file name to identify your export file. Make sure you have the “Replace duplicates with items exported” option selected. Click Finish when you are ready to move on.


6. The process of exporting your selected email account or folder will begin. A prompt will appear to create a password to protect your new PST file, but it is not required. Password protect your files if necessary.


Archive OST Files

You can also use Outlook’s Auto Archiving feature to create a PST file with a copy of all the contents from an OST mail account. You should note that if you have contacts as part of the OST file, then these cannot be archived.

Scheduled Auto Archive

1. From Outlook’s File menu, select Options. In the Outlook Options box that pops up, select Advanced from the list to the left and then the AutoArchive Settings button to configure how Outlook will create your PST archive file.


In the new dialog box that pops up:

  1. Check all of the checkboxes.
  2. Set how far back you want the system to archive files in Clean out items older than by inputting a number and selecting a time frame (days, weeks, months, etc.).
  3. Make sure the Move old items to: button is selected, and then click Browse to choose where to save your archived files.
  4. Once you have configured everything appropriately, click OK to close the AutoArchive Settings.

Now that you’ve configured how the archiving feature will work, Outlook will create a PST archive of your mail account based on your settings.

Immediate Auto Archive

Alternatively, you can start the process immediately.

1. Go back to the File menu, click on Tools, and then Mailbox Cleanup.


2. In the box that appears, click AutoArchive to start the archiving process immediately.


Using Software Tools to Convert OST to PST

While there are many free and paid tools online to convert an OST file to PST, you’re better off sticking to the official methods for the conversion. If you choose to use a program for this process, make sure to do your research and avoid downloading suspicious-looking files that may contain malware, which would corrupt your files and compromise your system.

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Avatar for Marho Atumu

About the Author: Marho Atumu

Marho is a Community Support agent at The Events Calendar and enjoys helping people discover how information technology can provide great solutions to their everyday problems. His career in IT can clearly be traced to his love for all things science fiction.

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