I have reproduced the issue and found that the HTML body of the MSG message is being replaced with text, the images are not removed but they are not added to the output PDF document. I have done source and output MSG comparison and found 5 differences. I have shared the results with the development team.
Unfortunately, I can’t reproduce issue with Sender Email, it looks fine to me in the output PDF document and I can see that it is not changed by Metadata or Conversion - test-converted.pdf (42.5 KB). Can you please clarify or share your output file.