I would recommend you use the MacSonik EML Converter. Recently, I used this utility to convert EML files into multiple file formats and I'm amazed by its performance. It can convert EML files to PST, MBOX, EMLX, MSG, PDF, GIF, JPG, JPG, TIFF, HTML, MHTML, PNG, DOC, DOCM, DOCX, and JSON. The tool has multiple advanced features like Convert Single/Multiple EML File which enables users to convert single and multiple EML files into different file formats and email clients. It also has Smart Preview before the Conversion feature users can preview the emails during the conversion process with attachments.