To convert multiple OST files into PST format I will recommend you try DataVare OST to PST Converter. It is designed so that the user can quickly convert many OST files to PST and then access the OST data in Outlook. This user-friendly program can convert OST emails with attachments to PST format. This program works seamlessly with any version of Microsoft Outlook and Windows operating systems. This is the best tool for users who are looking to convert OST files to PST format.