Published and built meticulously by USL Software, the converter turns the most demanding process into a simplified job that any one can do without efforts or going through myriads of complex manual setups. The Most Qualified Microsoft OST to PST Converter Online OST and PST are data files associated with. But often, the corruption of OST can render them inaccessible, although with the data perfectly reserved inside them. At other times, failing to make the distinction between OST and PST can lead to the users mistakenly deleting their email account and PST files, assuming the data can later be restored through OST. It cannot be. OST is more like an internal functioning data file for Outlook than a data file like PST. OST cannot be manually imported or in fact, cannot be operated in any way other than Outlook automatically using it for internal processing.