Easy method to convert multiple large OST files to PST without any change or losing data by downloading the most popular third-party tool of KDETools for OST to PST Converter tool. This securely export entire OST file data into Outlook PST file and various file types such as Zimbra, Gmail, PST, EMLX, NSF, HTML, MSG, vCard, MBOX, vCal, PDF, EML and etc. file types and with cloud applications such as Office365, Live Exchange Server.

Features of Outlook OST to PST Converter-

Batch Conversion option

Users can save all OST files into a single file or Convert a single OST into a single PST file.

There are no size restrictions for OST to PST conversion.

User can split PST file into smaller files.

More info- 

How to Convert OST to PST