Microsoft Outlook and Exchange save all their data, including email messages or calendar entries to proprietary file formats, namely PST and OST. Opening orphaned PST and OST files is not possible without Outlook, unless you have a dedicated application and there are a few viewers to choose from. One of them is simply named OST PST Viewer.

This particular application manages to open PST and OST files, enabling you to preview the data they store. It enables you to load one or more files, carefully placing each one in the left-side panel, with all its components. By default, these include inbox items, sent messages, deleted mailbox entries, and the outbox content. However, if the mailbox has additional folders, all of them are revealed.

As its name clearly suggests, the application is a viewer and nothing more. In other words, you can use OST PST Viewer to open and view the content of your PST or OST mailbox in read-only mode. This means that you are not allowed to make any changes to the mailbox content, therefore you cannot delete mails or move content around.

Aside from emails, OST PST Viewer also extracts calendar entries from the input files, as well as the list of contacts, tasks, notes, and the list of folders. The application features advanced built-in search, which really comes in handy when dealing with a large mailbox. There are various search criteria you can apply, which allows you to find certain messages, for instance the ones that are flagged or have attachments.

Attachments in emails can be easily saved locally, with the click of a button. Moreover, all the items in the mailbox can be exported to various formats, including MSG, ICAL, VCF, PST.

OST PST Viewer opens Outlook data files outside Outlook, allowing you to view the content of the mailbox and export it easily. Furthermore, it can export the contacts list, the calendar and other email folders, all with just a few clicks.