Convert Email to HTML in Java | https://blog.aspose.com/2021/04/05/convert-emails-to-html-in-java/

eml-to-html.java

// Load the EML/EMLX file to be converted
MailMessage message = MailMessage.load("email.eml");

// Save EML as HTML 
message.save("Saved File.html", SaveOptions.getDefaultHtml());   

msg-to-html.java

// Load the MSG file to be converted
MailMessage message = MailMessage.load("email.msg"); 

// Save MSG as a HTML 
message.save("Saved File.html", SaveOptions.getDefaultHtml());