What is OST and PST files in Outlook?

This article will share important information about different file formats regarding the Outlook email client. This article will be much helpful for individuals or organizations that they use Outlook email clients to send and receive email messages as a communication medium.

Upon configuring your email account in Outlook, you, as a user, create a local copy on your device. This local copy facilitates access to previously synchronized email messages, contacts, tasks, and more, even when you’re offline and not connected to the internet.. A local copy can be in an OST or PST file format, depending on your configuration process.

What is an OST file?

This file is created when Cached Exchange Mode is enabled while configuring email accounts in Outlook using IMAP, Outlook.com, Office 365, and Exchange accounts.

Notes: Even after configuration with IMAP account, Outlook makes a PST file to store the email database in the prior Outlook 2010 version.

What is a PST file?

PST is another file format that Microsoft Outlook uses to save users’ mailbox data. This data file type is created when users configure their email account in Outlook and choose the POP/SMTP standard type.

OST files become useless when

Case 1: When you want to share your email information or database with another device, Outlook doesn’t support this task. It is possible only with the help of Free OST viewer tool.

Case 2: If for some reason, your Outlook profile is removed from the Exchange server, you cannot access your stored information in the OST file.

Case 3: You cannot recover anciently deleted email items from the Exchange Server. You will lose deleted emails or Other Outlook items forever.

Case 4: When you reach the maximum storage limit, your OST file becomes inaccessible. You need to back up in PST format to free up space for new email items.

Case 5: Due to unforeseen circumstances, the Exchange Server might crash, causing damage or corruption to the Offline data files. Consequently, you will need to repair the OST file to regain access to previously downloaded items.

PST files become more useful when

Case 1: If you have stored the email items in PST format, you can easily send it on another device to open and read the PST file in Outlook.

Case 2:In case you inadvertently delete any email items from the mailbox, you can readily recover them from the Exchange Server.

Case 3: Deleting or removing the Outlook profile through the Exchange Server doesn’t impact the stored Outlook items.

Case 4: The stored email database in a PST file mailbox does not take space in Exchange Server. So Exchange server works uninterruptedly.

Case 5: You can easily repair a damaged or corrupted Outlook data file (.pst) by utilizing a third-party OST repair tool or the built-in repair tool within Outlook.

Difference between OST and PST files

OST file stands for offline storage table and PST file stands for personal storage table.
OST file uses the .ost extension and PST file uses the .pst extension to save the email database in a local file.
The default location of the OST file is C:\Users\user\AppData\Local\Microsoft\Outlook, and the PST file is stored in Documents\Outlook files.
You can’t apply password protection to OST files, but PST files can be secured with passwords. In the event of password forgetfulness, third-party password removal tools can offer assistance.

Final verdict

After analyzing both Outlook data file formats, we can easily conclude that the OST file has many disadvantages in saving email information compared to the PST file format. So I recommend you use PST format instead OST file. If you have an OST file, convert OST to PST file format on an urgent basis to avoid undesired circumstances.

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