If you need the best tool which can convert OST files to PST in Outlook 2010, you can try the eSoftTools tool. This tool is 100% tested from anti-virus and online scanners. It can migrate all email data like a journal, task, email inbox, temporarily deleted files, notes, appointments, contact, and many more. It can split the PST large file into the small format of PST and manage all data without making any changes. This tool provides to the user various formats to convert OST file into PST, EML, EMLX, Gmail, Office 365, vCard, MBOX, MSG, HTML, etc., if you have any doubt so, can download a free demo file to convert 25 items from each OST file into the folder.