We talk a lot about open rates for email marketing, but do you know what an open rate really is or how reliable the statistics are on open rates?  Let’s review.

Open rate = number of emails opened ÷ (number of emails sent - bounces)

For example, if Jessica sends out 100 emails, 12 of which bounce and 22 are opened, we would find her open rate as follows:
Open rate = 22÷(100-12)
Open rate = 22÷88
Open rate = .25 or 25%

25% is a fairly average open rate, but how accurate is this number?  Well, here are a few things you want to keep in mind:  the way that open rates are generally calculated is through a small piece of code that requires an image to be downloaded from the server.  If images are not enabled on a reader’s browser then the open will not be counted.  On the other side, if a user has a preview pane that shows images, the email will show as having been opened whether or not the user ever actually looked at the email.

Now, you can certainly affect this by asking your readers to select their email provider’s version of “always display images from this sender” and adding you to their recognized list so that they are more likely to show up in your open rate.  You should also figure that there will always be a slight margin of error as well.  That being said, open rates remain a solid way for opt-in email marketing senders to judge the effectiveness of their campaign.  It can also be used to inform senders as to which types of subject lines or sending schedules are most effective.