Great data, although it leaves out some useful bits to the formula, such as how loyal readership is to a certain company or individual sending the email.
If the email were going out to random folks, it would be a much more accurate survey.
This flies in the face of mannnny years of copywriting wisdom. I guess that's good in a way. Things are changing as much as ever and there's still opportunities to be had.
Basically, make it look like something people want, not spam.
Advertising copy gets tested since decades. Read "Scientific Advertising" by Hopkins from the 1920s.