Comment Spotlight: Open Rates and Image Blocking

I read an article on Problogger this week that talked about different ways to respond to comments, including responding in a separate blog post.

This is a great way to make sure as many people as possible benefit from discussions that they might have missed in a post’s comments, and something we should have started doing a while ago. (Thanks for the reminder, Darren!)

For our inaugural Comment Spotlight, I’d like to address an important point about tracking your message open rates:

How Does Image Blocking Affect Open Rates?

In response to our post on MarketingExperiments’ study on different styles of HTML message, Shiva asked:

“Doesn’t anybody face the problem of images being blocked? In Gmail and Yahoo the images in the html mail are blocked by default, and the user has to explicitly click on a link like “Display images below” to see the images. Doesn’t this affect the open rates of html mails? Could you please address this?”

Shiva’s absolutely right — if a user has images disabled, the one-pixel image used to track message opens won’t be displayed, and an open won’t be recorded for that user.

On top of that, if you have readers who scan messages using a preview pane, and they have images enabled, you could be recording opens for people who aren’t actually reading your messages.

So… what does this mean for you as you look at your stats?

It’s Not Where You Are, It’s Where You’re Going That Matters

You might think that since some people read your message but don’t record an open, and other people do record an open, but don’t actually read your message, that open rates are useless.

And to be honest, if open rates are all you use to track the effectiveness of your messages, and if you’re only looking at open rates in absolute terms, then well… they probably are useless.

If, on the other hand, you:

Compare them to your clickthrough rates
Track changes in them over time

then they are quite useful, primarily to identify trends in subscriber responsiveness. For example:

If your open rate falls over time, it may mean your subscribers are beginning to ignore you — but why? (Are you not providing the same value? Are your subject lines not getting their attention?)
If your proportion of clicks-to-opens increases over time, it may mean that your message body is doing a better job of spurring readers to action.

Open Rates Tell You The Most In The Short Run

The key assumption in reading into those trends is this:

For a given group of subscribers, even if you don’t know how many people are blocking images, or how many have them enabled but don’t actually read your message, the proportion of each group isn’t likely to change much in the short run.

A year or two from now? Sure, it’s quite possible that a different proportion of your readers will be blocking images, or will have them enabled but not actually read your message. So I wouldn’t compare your open rates from 2005 to today and expect to deduce anything significant.

But let’s face it: “In the long run, we’re all dead.”

Use open rates to measure subscriber response and improve your email marketing campaigns in the short run, so you’re still around for the long run.