To merge PST files in outlook. use Merge Outlook PST Tool. This application is a very advanced software to merge PST files. This software takes almost no time to finish merging multiple files. Users do not have to worry about the file size as this tool merges files regardless of their size. It does not make any changes in the data saved in the PST file. Merge Outlook PST Tool is compatible with all the versions of Windows OS and MS Outlook. Visit here for more info: https://www.softakensoftware.com/merge-outlook-pst.html