SysTools OST Viewer tool allows a user to open multiple OST files with attachments. OST file opener generates an instant Preview multiple OST mailbox emails with attributes as From, Subject, To, Sent, Received Date and Size in bytes. OST file reader has an inbuilt attachment preview panel which preview OST file's attachments of any type like images, docs, files, etc. View OST file items such as emails, contacts, calendars, tasks, etc.