Even that's not sufficient. Consider an email client that doesn't parse images until you interact with the message. So you click on it, realize it's dodgy, but it's too late now because all the complex bug prone machinery has already been triggered.

Or my favorite, I marked an extremely suspicious message with what was almost certainly a malicious attachment as junk in a certain BigTech webmail client (the only other option was phishing which it most certainly was not) and it "helpfully" opened the unsubscribe link in my local browser without first asking me for permission. It's difficult to imagine the level of incompetence and dysfunction required to not only write but review, approve, and deploy such a feature in a security and privacy sensitive context.