You can view large OST files without Microsoft Outlook using the SysInfo OST Viewer Tool. Simply install the software, launch it, and load the large OST file from your local system. The tool supports oversized OST files and allows you to preview emails, attachments, contacts, calendars, notes, tasks, headers, MIME data, and RAW HTML without requiring an active Outlook, Exchange, or Microsoft 365 profile. You can load single or multiple OST files simultaneously while retaining the original folder hierarchy. The software can display up to 20,000 emails in a single folder batch, making it suitable for reviewing large mailboxes. Its Smart Search feature helps quickly locate specific emails using From, To, Subject, attachment, and date-range filters. After previewing the data, you can export it to PST, PDF, EML, MSG, MBOX, or CSV formats. The tool also works on Windows and Mac, making it a convenient option for users who need to access large OST files without Outlook.
Read More - https://www.sysinfotools.com/recovery/ost-file-viewer.php