Converting OST files to PST becomes essential when Outlook data turns inaccessible due to profile deletion, server issues, or file corruption. While Microsoft offers a limited inbuilt export option, it works only with healthy and active OST files. For advanced recovery needs, professional third-party tools provide a secure and reliable solution. This article explains free Microsoft methods, their limitations, and why professional OST to PST converters ensure accurate, zero-data-loss mailbox recovery.