Cases When Stellar Converter for OST Is Used The software also provides additional saving options, such as EML, PDF, RTF, and HTML. You can further use the software to convert encrypted or password-protected OST files into PST. In this review, we’ll discuss about Stellar Converter for OST software, its features, and how it works. The software also allows you to directly import the file into an existing Outlook profile, Office 365, or live Exchange server. Stellar Converter for OST in one such OST to PST converter software that you can use to convert an inaccessible, damaged, or orphaned OST file into PST. After conversion, you can import the PST file into any Outlook account and access the mailbox items. However, you can use an OST to PST converter software to convert an inaccessible, damaged, or orphaned OST file to PST format. Thus, you can’t open, or access an Outlook OST file on any other Outlook profile. An OST file can be accessed only through an authorised MAPI profile. The encryption key is saved in the system registry on server and MAPI profile. Unlike PST, OST or Offline Storage Table is encrypted by default with MAPIEntryID GUID. OST and PST are Outlook data file formats used by MS Outlook for Windows to store a local copy of the mailbox items on the server.