Yes. I hope we've learned that any kind of interpretation of text is a security problem. Active emails (NeXTmail, ActiveX) had mind boggling problems. HTML email allows phishing to exist. I'm starting to feel skeptical about Unicode homographs, and byte order marks sound like another slow motion disaster like segmented memory and magic device names (CON, LP, etc). Heck, even things like vi "mode lines" can be a problem.
Plaintext. No interpretation.