So... someone you know consistently derps at email. Perhaps they "Reply All" when they shouldn't; perhaps they can't figure out calendaring or maybe they're just plain stupid and don't understand that phoning to tell you that they've sent you an email is utterly moronic.
For every way someone is stupid with email, we have a link for you to send them.
Pick their offence from the list below.
Fool: Hi! I've just sent you an email about...
You: Then why are you calling me, you fool?!
For those who can't tell the difference between their email client and Google's search box.
Did everyone need to hear that? Really? This one's for the person whose big-R behaviour needs a big stick.
 Okay, who are we kidding? There are infinite ways for an infinite number of people to be infinitely, infinitely, really, really, tautologically stupid. These are just the most common ones.