How do you open an OST file in Outlook?

Picture this… You need to access your emails, but you’re stuck on a plane without Wi-Fi. Or you’re at home, but your Internet connection is down. Thanks to the OST files automatically created by Outlook, you can still access all your data. The OST file stores your data as a local backup. However, you cannot open an OST file in Outlook directly. First, you have to convert it into a PST file. Read on to find out how to do this, and what you need to bear in mind.

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Outlook data files: What is an OST file?

When you add a new email account to Outlook, a local copy of your data is automatically saved on your computer. The local file is known as an Offline Storage Table, or OST file for short. It allows you to access your emails, contacts, and calendar even if you have no Internet connection. Outlook will automatically synchronize your data when you go online again. For more information about OST files, check out our article dedicated to the subject.


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How to open OST files

The latest version of Outlook automatically creates an OST file for you, but it’s not always easy to find! Here’s where to look. In Windows 10, open Windows Explorer and go to: <Drive>\User\<Username>\AppData\Local\Microsoft\Outlook.


You may not be able to see the “AppData” folder. This is because it is hidden for security reasons. If this is the case, go to the “View” tab and select “Hidden items”.

Outlook will automaticallyaccess this file if your Internet connection cuts out. You cannot open the OST file directly. However, if you have several OST files, you can define which file Outlook to use. To do this:

  1. Open the Control Panel.
  2. Go to “User Accounts”.
  3. Select “Mail (Microsoft Outlook)”.
  4. Click on the “Email Accounts…” button.

If you have more than one OST file, you can set one of them as the default file. Outlook will then use this file automatically the next time your computer disconnects from the Internet. Multiple OST files are mainly useful for creating Outlook backups. Also, if your email storage space is full, you can use an OST file to archive your data and save it on your computer.


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Converting an OST file into a PST file

An OST file is simply a local backup of your data. You cannot open an OST file on another computer. If you want to access your data from another device, you have to convert the OST file into aPST file.

Exporting an open OST file using Outlook

There are several ways to do this. One option is to download a special OST converter, which lets you select an OST file, convert it, and save it. Alternatively, if you’d rather not download additional software, you can do the conversion directly using Outlook. The instructions below are for the current version of Outlook (2019).

Step 1: Open Outlook. Sign in if you haven’t already. Click on “File” at the top left of the ribbon.

Steps 2 and 3: In the blue menu bar on the left, click on “Open & Export”, then click on the “Import/Export” button. A pop-up window will appear.

Steps 4 and 5: In the pop-up window, select the third option: “Export to a file”, then click on “Next” in the bottom right corner.

Steps 6 and 7: In the next window, select the “Outlook Data File (.pst)” file type. Click on “Next” to continue.

Steps 8, 9, and 10: Select the folder that you want to export by clicking on it. Make sure that the “Include subfolders” option is selected. This will ensure that all subfolders and their contents are exported too. Click on “Next” to confirm.

Steps 11, 12, and 13: Click on “Browse…” to specify where the PST file should be saved, or confirm the location suggested by Outlook. Either way, make sure that you know where the file is saved! Decide whether or not you want to export duplicates, then click on “Finish”.

Outlook will now suggest that you create a password to protect your file. If you decide to set up a password, you will be prompted to enter it several times during the export/import process. If you prefer not to use a password, simply click on “OK” to run the export process. This may take a few moments.

Opening a PST file in Outlook

The export process is now complete, but to access your data while offline, you need to import the PST file. The first few steps are the same as for the export process: Go to “File” > “Open & Export” > “Import/Export” to launch the Import and Export Wizard.

Steps 1 and 2: This time, select “Import from another program or file”, and click on “Next” to confirm.

Steps 3 and 4: Click on the file type that you want to import – “Outlook Data File (.pst)”. Then click on “Next” again.

Steps 5, 6, and 7: Click on “Browse” to find the previously created PST file. Choose whether or not to import duplicates. Click on “Next” to confirm your choice.

Steps 8, 9, and 10: Finally, select the folder that you want to import. Remember to select the “Include subfolders” option. Finally, click on “Finish”. You can now access the OST file without any problems.


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