Alison Overholt wrote Intel's got too much email in the March 2001 issue of Fast Company. I don't exactly know why it boiled to the surface for me, but I thought the list of do's and don'ts was a good one.
Of course, this was in that innocent age when viruses and spam didn't comprise 90% of email traffic. I'm hopeful that we'll return to that state of affairs within a year — the current spam/virus situation simply can't deteriorate much further before the big kids (Microsoft, Yahoo, etc.) arrive at a mutually-agreeable technical solution.