Please clarify what you mean by "shows properly" and "does not show properly" -- I don't have a crystal ball.
And have you really tried *all* other email apps?
It would be great if you could send me a sample message -- to kmansoft / gmail / dot com -- and I need you to either:
1 - "Forward as attachment" in a desktop mail app (so the original message is attached as an .eml file).
OR
2 - Web mail -> open message -> "show original" or "view source" or similar -> save to a text file (plain text, no MS Word or LibreOffice please) -> send as attachment.