Treat eml files like PDFs. Just show the to, subject, sent date, and body fields as if it were a PDF like document. I know that there have been a number of discussions on this subject, and the hangup seems to come down to issues with an email client. The common denominator is the eml file format. Allow us to attach it to a thought and view it's contents without launching an external app. Let us worry about how we get the eml file in the first place.