Note: You must have Outlook 2003 or higher versions installed on your local computer to use the method in this guide.

If your OST file is created by Microsoft Outlook 2002 or lower versions, and its size reaches or exceeds 2GB, you will encounter the oversized OST file problem and cannot operate the OST file any more. In such a case, you can use DataNumen Exchange Recovery to scan the oversized OST file, retrieve all the data in it, and save them into a new PST file in Outlook 2003 unicode format that has no 2GB size limit any more. Then you can use Outlook 2003 or higher versions to open the new PST file and access all its data without any problems.

Start DataNumen Exchange Recovery.

Note: Before converting the oversized OST file with DataNumen Exchange Recovery, please close Microsoft Outlook and any other application that may access or modify the OST file.

Select the oversized OST file to be converted:

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You can input the oversized OST file name directly or click the Browse button to browse and select the file. You may also click the Find button to find the oversized OST file to be converted on the local computer.

DataNumen Exchange Recovery will save the converted data as a new file in Outlook PST format so that later you can use Microsoft Outlook to open and access the converted data. And by default, the new PST file name is xxxx_recovered.pst, where xxxx is the name of the source oversized OST file. For example, for source oversized OST file Source.ost, the default converted PST file name will be Source_recovered.pst. If you prefer to use another name, then please select or set it accordingly:

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You can input the output PST file name directly or click the Browse button to browse and select the PST file name.

Since we want to convert the oversized OST file into a PST file in Outlook 2003 format, which doesn’t have a 2GB size limit, we must set the format of the output PST file to “Outlook 2003/2007” in the combo box blank beside the output file edit box. If you set the format to “Outlook 97-2002” or “Auto Determined”, then DataNumen Exchange Recovery may fail to process and convert your oversized OST file.

Please note you must have Outlook 2003 or higher versions installed, otherwise the whole conversion process will fail.

Click the Start Recovery button, and DataNumen Exchange Recovery will start scanning and converting data from the source oversized OST file to the destination Outlook 2003 PST file. Progress bar
DataNumen Access Repair Progress Bar

will indicate the conversion progress.

After the conversion process, if any data can be converted successfully, you will see a message box like this:
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Now you can open the converted PST file with Microsoft Outlook 2003 or higher versions, and see the data of the original OST file have been converted into the new PST file.

Note: The demo version will display the following message box to indicate the success of the conversion:

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Then you can open the converted PST file with Microsoft Outlook 2003 or higher versions. However, for each converted message, its contents will be replaced with the following demo information:

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To get the actual converted contents, please order the full version.