? OST file is a cached Offline Storage File of Microsoft Outlook which is automatically created when we configure an account at client end, connected to Exchange Server. OST file holds mails, notes, calendars, journals attachments and all the items of MS Exchange Server mailbox folder. OST and PST both files are created at same location and works same. PST file is directly synchronized with network instead of Microsoft Exchange Server and user can read the archived data. So if we want to migrate the OST file out of Exchange Server environment we need to convert OST to PST so that we can access the mails and documents without connecting to Exchange Server. Extract OST to PST can be carried out in local system without using any third party tool. You can Converting OST to PST: Here is a step by step procedure for OST to PST conversion: Open the Microsoft Outlook. Click on File menu. Choose the Import and Export Wizard or presst. Click on Export to a file option from the list. >>Next Select Personal File Folder (.pst). >>Next Choose the Items to be exported or Click on parent root and check the Include subfolders option. Choose the target folder to save the items. Finish The above method is based on Microsoft Office 2003 Professional Edition. Options may vary in Microsoft Office other versions. Disadvantage of Manual OST to PST Conversion: You can convert OST to PST till the time you are connected to Exchange Server. If you are disconnected from Exchange Server or your Exchange Server is damaged then you need third party OST to PST conversion tool. Free OST2PST Converter Tool: SysTools OST Recovery is an OST to PST conversion software. Free OST2PST converter program provides you the facility to repair OST file for free. This tool converts OST file to PST, MSG, and EML file format. OST to PST File conversion with the help of this software tool is extremely simple and effective.