I get where both of you are coming from, but there is one UX part of this I've found that is hard to solve. Inexperienced users want to be told what to do. You

I get where both of you are coming from, but there is one UX part of this I've found that is hard to solve. Inexperienced users want to be told what to do. You can't just throw information or warnings at them without giving them a way to act on it. Combine that with the fact that if the users even read the warnings they are going to only read a sentence at most, or just the first option. So when you show a warning like"you have never received email from this address before" users are going to ask what they should do. Is this dangerous? Did it come from my bank? I've had this bank for years! Does this mean the email is a hacker!? If you say "it can be dangerous, but it also can be just a new email" that will be read as "yes this is dangerous" and now they will learn the hard way that it is safe, and your warnings will have less weight in the future (they were wrong about this being "a hacker" once, they might be wrong this time too!) It's a really hard problem to solve, and the "easy way out" is to not show the information at all (no confusion if you just don't show it!) But that kind of just kicks the can to the user leaving them to determine if an email is "good" or "bad".