Sysinfo OST Viewer

SysInfo OST Viewer Tool is designed to open, read, and inspect Outlook OST files without requiring Microsoft Outlook, Exchange, or an active Microsoft 365 account. It provides access to healthy, password-protected, oversized, orphaned, and minorly corrupted OST files. The software also supports PST files and can load single or multiple files in ANSI and UNICODE formats.

The tool displays mailbox contents while retaining the original folder hierarchy. Users can browse emails, attachments, contacts, calendars, notes, and tasks, along with message information. Its six-tab preview presents Body, Attachments, Notes, Header, MIME, and Raw HTML details. Users can inspect message content, metadata, timestamps, and attachment information before exporting. The preview pane displays up to 20,000 email messages, subject to applicable product settings and license.

To locate specific messages, users can search by sender, recipient, subject, date range, or the presence of attachments. Date filters support saving all messages, including selected dates, or excluding selected dates. Text filters can narrow email results by To, From, and Subject. These options help users review large mailboxes without manually checking every message.

After previewing the data, users can export mailbox content to PST, EML, MSG, PDF, MBOX, or CSV. The software can also import OST data into Office 365 using OAuth 2.0 modern authentication or admin impersonation. During export, users can choose how attachments are handled: retain them, save them as pages, extract them separately, or exclude them. PDF output can be saved as individual files or merged into a single PDF. Folder hierarchy and email metadata are preserved during the process.

Additional options include duplicate email removal, custom folder names, destination selection, and skip/resume export for interrupted tasks. Activity logs record loading, scanning, and export operations, providing processing details for review and audit documentation. The software performs local, read-only viewing and does not overwrite the uploaded source files. It can work offline without requiring a live Exchange connection or uploading mailbox data to a cloud service.

SysInfo OST Viewer supports Outlook OST files from Outlook 1997 through Outlook 2024 LTSC and is available for Windows and macOS. Its editions include Single, Admin, Technician, and Enterprise. The demo version allows users to preview and export up to 100 emails per folder, so they can evaluate the file loading, preview, and export functions before choosing a license. The interface is designed for individual users, IT administrators, and organizations that need to inspect or export Outlook mailbox data.