No dilema here
I've been in some situations involving sensitive information. I would not have read the email. I would have forwarded it as routine business.
What's in the email is none of my business. However there was one situation where I did say something, it involved classified information being collected by a person that had no need to know, I stumbled upon it while doing maintenance and certainly reported it. I don't know what became of the "suspect" I never saw him again.