The most searchable query on the internet- How to Fix Outlook OST Synchronization Error 8004011D-526-80040115? I will discuss the best eSoftTools OST Recovery tool. It supports all window versions like win XP, win 7, win 8, win 10. It can recover OST files into PST, EML, EMLX, HTML, Office 365, MBOX, MSG. It’s 100% tested from anti-virus and online scanners. It has many amazing features like – Multiple Naming Conventions, Convert Encrypted OST file. It can also repair mailbox data items such as Emails, contacts, journals, tasks, etc.