After so many issues, one of my friends suggested the software Enstella OST to PST Converter software to convert Outlook Convert OST to PST Office 365. This software exports your OST files to PST very easy method and in multiple formats like EML, MSG, HTML, MBOX, vCard, EMLX, and other formats with all mailbox items like emails, contacts, attachments, images, journals, tasks, calendars, distribution lists, draft folders, etc. This software has many features available for the Enstella website. This software is Windows OS-based and also provides a free demo version for all users.