Open rate

Mark Brownlow over at Email Marketing Reports has been talking about open rates for a while. His point, one I fully agree with, is that open rate is not what you think it is. At best it is a measure of who is rendering your email. Today he links to a post from ReturnOnSubscriber. In this post, the author demonstrates that by using an alt tag saying “don’t you want to save 40%”, the open rate for an email increased 27% over previous sends.
But. Wait.
I would argue that there was no change in the number of emails that were opened and read. In fact, an alt tag can only increase your open rate if recipients are already opening and reading your mail. What is really being measured here is the number of people who load images, not the number of people who are reading your mail. Those extra 27% of people opened and read that email before they loaded an image. They had to! If the alt tag was to have any effect on open rates, then people had to read the alt tag!
Now we have this great increase in a statistic, but what does that actually mean? I know that open rates make marketers feel all warm and fuzzy, but HUF did not actually increase the number of people opening and reading his mail. The only increase was in the number of people rendering images. Much more interesting would be actual clicks or even sales. Does the increase in people loading images in an email translate into actual revenue? That’s the really critical measure.