If you wish to open an OST file from Outlook on a different machine. Directly opening an Outlook OST file on another computer is not possible. Convert an OST file to a PST file by downloading eSoftTools OST to PST Converter. The OST file can then be simply accessed on another system after that. This tool can convert between many different file kinds, including OST to PST, EML, EMLX, Yahoo mail, and many others. Accessing non-technical users is simple. You can convert any folder for free using the sample version for up to 25 files.