I don't think theres anything wrong with posting an email like that as no one here knows who the guy is, just that he's called Ryan.
Yes, I understand that part....but....(and it's just my own personal standard),
put yourself in the place of that guy? He may have actually liked her when they first met...he seemed a little shocked in the email that she was being so blunt about it...and he obviously thought she wasn't still married. If you liked someone, and even if they didn't like you, how would you feel if they posted something on the internet such as a personal email?
I just don't think I'd feel very comfortable not with the information, because yes, you are right, nothing identified him....it was more the act of doing it, I don't think I could do it to someone, let alone someone I'd had sex with, no matter how casual. That's just me.
I wasn't suggesting she remove the email, it just reminded me of how shocked I'd be if someone did that to me in an intimate conversation.