Microsoft Outlook, in the offline (Cached Exchange) mode, saves all the Exchange mailbox data in a local file named OST file. The changes made by the user in the offline mode are later updated to the server mailbox when the Exchange connection is re-established. As the OST file resides on the user’s computer, it is unaffected by Exchange Server crashes and disasters, Exchange mailbox deletions, etc. So, Exchange administrators and end users can use OST files to restore user mailbox data in the occasions of such eventualities.

Here are some situations when converting an OST file to PST becomes very helpful:

A few Exchange mailboxes get deleted from the server

Want to back up a few Exchange mailboxes

An Exchange user wants to rebuild his OST file, but the user has some unsaved data in the OST file

EDB files are inaccessible due to Exchange corruption, Server crash, etc. and users want their emails urgently

Instant Solution Try automated tool Kernel for OST to PST Converter to Convert OST File to PST, EML, MSG, Office 365, and Exchange.



There are multiple methods to convert any OST file into PST provided you can log in to Outlook with the same Exchange profile. Some native methods to convert OST to PST are presented here:

Method 1: Export mailbox as a PST file

Login to Outlook with the Exchange account that was used to create the OST files. And to export the OST mailboxes to PST, follow the simple procedure:

Go to Files >Open & Export and click Import & Export. Select Export to a file; then click Next. Select the second option—Outlook Data File (.pst)—and click Next. Select the folder which you want to export and click Next. Browse the location where you want to save the new PST file and choose the options regarding the duplicate items.

Note: There is an optional choice to provide a password to the PST file, but you can easily move ahead without choosing it.

Method 2: Use ‘Archiving’ to save OST emails to PST

By enabling the Auto Archive method in Outlook, you will be able to save the items of OST file in a separate PST file. This method helps you to keep the size of your mailbox manageable. When the size of the mailbox grows and there are multiple messages that are older and you do not require them to be in the mailbox, then you can put them in the archive folder easily. Follow the simple steps to enable auto archiving in Outlook.

Launch the Outlook application, go to File, and click Options. Go to Advanced and click Auto Archive Settings. Now select the number of days in which you want to run auto archiving. Select the folder to save the archived file; also, provide the archiving options and finally click OK.

With this, mailbox items from your OST file will be saved to the PST file as per your archiving settings.

Convert OST to PST without Exchange profile or server connectivity

Kernel for OST to PST is a professional tool which can freely convert 25 items from each OST folder to PST. Its advantage is that it can convert offline OST files to PST without an Exchange profile or Exchange Server connectivity. It has a highly user-friendly interface which lets the user select OST file(s), recover items including the deleted ones, and convert them to PST format. Also, it can convert multiple OST files to PST at a time. Let’s see the working of the tool:

Open the OST to PST tool. It will open a wizard to select single or multiple OST files. Select the OST file from its location. When the tool displays the OST file content, you can choose a folder and view its content in the preview pane. To convert the OST file into PST, click the Save option on the toolbar. To save in PST, click PST file (MS Outlook) as the Output type. Select the filters – From, To, Subject, Folder name, Item type, and Date range. You have the option to split the PST file after a certain size. Provide the required details. Browse the destination path and provide the required details. Lastly, click Finish. When the conversion is complete, the tool shows a message showing the PST file name and its location.

You can manually convert OST to PST only when you are using Outlook with the original Exchange account. But the software converts the OST into PST format even without the original Exchange profile and Exchange Server connectivity. Also, it provides many advanced filtering and saving options. Also, you can convert 25 items from each folder to PST for free.

Watch Video: To View the complete process of OST to PST Conversion

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