I recently stopped using Outlook, and now I need to access my old emails in a client that supports only MBOX format (like Thunderbird or Apple Mail). Unfortunately, all my mailbox data is in OST files, and Outlook is no longer connected to the Exchange server. I am looking for a reliable way to convert OST to MBOX without losing any emails, attachments, or folder structure. Free or paid solutions are fine, but I prefer something that ensures data integrity. Has anyone here tried this before? What is the best method or tool to perform a safe OST to MBOX conversion?