If you want to read EML files as PDF, then you should use EML to PDF Converter for complete file conversion. There are various reasons for the failure of the manual method to transfer EML as PDF format and sometimes import is successful but the attachment files are not included within it. So the better option is to use the automated tool for easy save of files in bulks.
Visit this for details: https://www.mailconvertertools.com/eml/