> For instance, why do we not see in every client a big warning at the top saying something like: “NOTE: YOU HAVE NEVER RECEIVED E-MAIL FROM THIS INTERNET LOCATION BEFORE.”?
Because that is way too dangerous a policy. Recently, I moved, and in creating online accounts for online bill pay, I got confirmation emails from each of my utilities. Saying that they're spam just because you've never received email from them would cause most people to be unable to find these confirmation messages.
> And, why by default do they insist on making everything look “simple” and “clean” at the expense of helping users to do even the most basic validation? They show senders as short names like “Facebook” when CLEARLY the message is coming from facebook.spammer.com or whatever when you do even the slightest digging into the original message.
Uh, my email client doesn't do that. If the email address isn't priorly known, it shows the email address instead of the display name.
> Why are “rules” so complex, since damn near everybody needs them for basic sanity? There ought to be a button in every message saying something like “Mark Every Future Message From This Sender as Junk”, and similar short-cuts.
Most spammers don't reuse the same email addresses. You end up with a lot of useless rules. Bayesian spam filtering is much more effective, for example, and requires very little user action.