Convert Outlook OST to PST File - Version 3.01 When you work offline, you can easily add and modify the information of an .ost file. The OST file contains entire offline information of Exchange server, but when corruption occurs into OST file then entire items get corrupt. To get back your Exchange OST data OST converter is best option. Using this tool you can recover and convert Outlook OST to PST file format. This software is also best to convert Outlook OST to EML & MSG formats. Software support all the version of Exchange server as yet MS Outlook. You can download free demo of OST converter software which allow you to convert 5 Outlook OST to PST file FREE. For complete conversion of OST file you need to purchase full version at just $99 only.