You can easily convert your OST files into PST format by taking help from DRS OST to PST Converter. This software can convert OST files into different file formats and email clients. The tool is very easy to use and can perform the conversion task in very less time. You can download its free demo version and check its functionality.
To know more , visit - https://www.data-recovery-solutions.com/ost-to-pst-file-converter.php