Larry Chase, publisher of Web Digest For Marketers, followed up with this observation:
Hi Morty,So now there's a new variable in the test. Not only what gets more eyeballs or clicks, but which clicks actually result in more sales!
In solo emails I have found the Johnson box to be very effective, maybe because so many people view their emails in Preview Pane in this "give-it-to-me-quick" medium. My guess is the PS works better in print because readers don't have to scroll all the way down a printed page since they can just give the whole communique the one-over-light as they drop down to that PS. Still, the online PS seems to have its share of clicks. Maybe that's because of the reader who is absorbing the email message from top to bottom.
An interesting test would be to see which clicks convert to sale. My bet is the clicks from the PS are more likely to buy something.
PS: In case you missed it, see Steve O'Keefe's comment on spam, subject lines and a quest for "irresistible words."