Take the help from Advik EML to PST Converter. This software is one of the best tool to convert EML to PST for Outlook 2021, 2019, 2016. 2013 and other versions. It will batch convert EML files to PST without losing data. The software is available for free trial.

Steps to convert EML to PST are follows.
  1. Run Advik EML to PST Converter in your PC.
  2. Click Add File and add EML files.
  3. Select PST as saving option.
  4. Click Convert button to start process.
Done ! This is how you can combine eml files to pst format.