Undercover Economist

Seth Godin’s email checklist:

1 Is it going to just one person? (If yes, jump to #10)
2 Since it’s going to a group, have I thought about who is on my list?
3 Are they blind copied?
4 Did every person on the list really and truly opt in? Not like sort of, but really ask for it?
5 So that means that if I didn’t send it to them, they’d complain about not getting it?
6 See #5. If they wouldn’t complain, take them off!
7 That means, for example, that sending bulk email to a list of bloggers just cause they have blogs is not okay.
…
10 Have I corresponded with this person before?
11 Really? They’ve written back? (if no, reconsider email)…

The list goes on to 36 and almost all of the advice looks good to me.

Beyond the practicality of the checklist, it raised a question in my mind. Some of Seth’s advice was routinely flouted in the early days of mass email (I’m thinking 1995-1999). For instance, many people forwarded jokes and virus warnings. These days they are rare, especially as a proportion of all the email that is sent. Other advice (such as, “don’t admonish people not to print this email”) would have been superfluous ten years ago and is now very widely ignored.
So my question is, what determines why some bad email habits die out and others thrive and multiply? Or is this just the unpredictable outcome of a mysterious process of evolution?