You can convert EML to PST manually via Outlook email client. First of all, install Outlook application on your system and create a new folder in Outlook. Now, drag & drop EML files in this newly created folder. After that, export EML files to PST using the import-export feature. Hence, you can convert EML to PST file format using Outlook but it takes lot of time to complete the process. However, you can directly convert EML files to PST format using any third party tool in a few seconds.