To open and import multiple EML files into Outlook, you have several effective methods to choose from eSoftTools EML to PST Converter Software. This software allows you to import multiple EML files into Outlook in one go, maintaining the original folder structure and formatting. Additionally, it converts EML files to PST format, which is natively supported by Outlook, simplifying the import process.

More info - https://www.esofttools.com/eml-to-pst-converter.html