What do email open rates mean?
Previous: Email Open Rates Guide
When your email service sends out your email, they include a piece of code in each one requesting the display of a tiny, transparent (i.e. invisible to the viewer) tracking image.
When the recipient's browser or email reading software (an email client like Outlook Express) tries to display the email on a screen, it reads that piece of code and sends out a request to the email service for the tracking image.
The email recipient is unaware of all this, of course. He or she never sees the image, as it's tiny and transparent: the whole process takes place in the background.
When the service receives the request, it records it and uses it as an indication that the recipient has "opened" the email.
By giving each email its own unique tracking image, the service can even tell which email was opened. So not only does it tell you how many emails were "opened," but it also tells you exactly which recipient's emails were opened.
This sounds great. If it wasn't for a but or three.
First, you now see that "opened" actually just means the recipient's software or browser displayed the email such that the tracking image was requested.
It says nothing about whether the recipient actually read or engaged with your email in any way.
So it is only a rough proxy for what you might call reader interest. (But better than nothing.)
Second, the tracking image can be activated without the recipient ever actually seeing the email at all.
Many email clients have a preview function, where part of the email is displayed below or to the side of the list of emails in your inbox.
So you can highlight an email on your screen and hit the delete button without ever looking at its content. But the preview function means the email client has tried to display the email and thus registered an "open."
So some of those recorded opens are from recipients who never even looked at your email.
Third, some recipients will read your email and an open is not recorded. Hah! Now we have the reverse case.
How does that happen?
Your email service can only track the open if that little tracking image is requested.
That piece of code is HTML code. So if your recipient gets text-only emails or has an email client that only displays text versions of emails (like many mobile devices), then the image code is ignored and never requested.
No image request means no record of an open. So your recorded email open rate misses out on those people.
And it doesn't end there. Many email clients now refuse by default to display images (see below). So they show the email in its entirety, but ignoring images. Again, the recipient could spend all day reading the email but an open is never recorded as the tracking image was never requested.
Many email services also overestimate the number of delivered emails. An email that ends up in the spam folder, for example, is still recorded as delivered by the email service. So some recipients who didn't open your email actually never got it in the first place.
Did they not open your email because of disinterest or because they just never saw it?
Clearly, we're in trouble. Not only do recorded open rates not tell us if someone actually read our emails. They can also underestimate or overestimate the true open rate!
Calculation
Even if we had an accurate way of measuring open rates, there's another problem: there are different ways of calculating them. In our earlier example, open rate is the number of opens expressed as a percentage of the number of emails delivered. That's the commonest approach.
Others, though, may express it as a percentage of the number of emails sent.
Some count an open every time an email is opened. So if someone "opens" the email, moves on, then goes back to the first email a day later, you have two opens from one recipient.
Some deal only in unique opens, never counting more than one open from each recipient. So the above scenario would produce a single "open."
As far as interpreting your own email open rates go, you just need to know how your service or software calculates your numbers. As long as you know how you calculate open rates, you can make better judgement calls on the meaning.
Calculation methods become a problem when people start comparing open rates across services or senders. More on that later (I warned you this was long!)
Relevancy
Finally, another apparent nail in the open rate coffin is the issue of relevancy. In the last century, tracking email marketing results was relatively underdeveloped. Open rates and possibly clicks were often the only thing that got measured.
As a result, open rates became established as the success standard of choice...by default. There wasn't much alternative. This became ingrained into the email marketing mentality. But is it really what you want to measure?
We'll see how it has its uses in a bit, but are "opens" really what you're trying to achieve? Even if you could measure opens accurately and meaningfully, aren't opens merely one step in a process which should end with the recipient taking some kind of action?
That's why you should emphasize those other metrics in your evaluations (clicks, downloads, purchases, registrations, whatever). Open rate is just one of the numbers you need to look at. Don't place too much focus on it just because its traditional and appears in all your reports.
Next: How to use email open rates
1. Email open rates guide
2.
What do email open rates mean?
3.
How to use email open rates
4.
Average email open rates
(why yours are different)
5.
How to improve email open rates