An OST file can remain on a workstation even after the associated employee account has been removed or the Exchange/Microsoft 365 mailbox is no longer accessible. In such situations, the file may still contain valuable historical information, but opening it through a newly configured Outlook profile is generally not a straightforward solution.

For organizations, this can become important during employee offboarding, internal audits, legal reviews, or the preservation of business correspondence. Emails may contain project discussions, customer communication, attachments, appointments, contacts, and other information that needs to be reviewed independently of the original mailbox.

A specialized OST viewer can provide an alternative way to inspect this information. Instead of depending on the original Exchange connection, the application reads the available data from the OST file and presents the mailbox folders in an accessible interface.

The SysInfo OST Viewer Tool  is designed to open and preview OST files without requiring an active Exchange Server, Microsoft 365 account, or the original Outlook profile. Users can load an OST file and navigate through available folders to examine stored mailbox information.

Email previews can include details such as sender, recipient, subject, date, message content, and attachments. The software can also display other mailbox components, including contacts, calendars, tasks, notes, and journals when those items are present in the OST.

Another useful capability is the option to export selected mailbox data into commonly used formats. Depending on the requirement, OST content can be saved as PST, EML, MSG, PDF, CSV, or MBOX. This can help organizations create accessible copies for archiving, analysis, or further processing.