Now, I know that all "Here’s The Thing" readers are hip to email ettiquette, but (cough) just in case you’re not, the always wise Guy Kawasaki has laid it out for us. If you don’t need this, pass it on to someone who does. I know you know at least one such person… My favorite tip:

Attach files infrequently. How often do you get an
email that says, “Please read the attached letter.”? Then you open the
attachment, and it’s a dumb-shitake Word document with a three
paragraph message that could have easily been copied and pasted into
the email. Or, even worse, someone believes that his curve-jumping,
paradigm-shifting, patent-pending way to sell dog food online means
you’ll want to receive his ten megabyte PowerPoint presentation? Now
that lots of people are opening messages with smartphones–sending
files when you don’t have to is a sure sign of bozosity.