When an email is sent to a recipient using the Total Send service, Total Send embeds a transparent, 1×1 pixel, GIF image in the email. This GIF image is called a “tracking pixel”. When the subscriber opens your email, all images, including the tracking pixel, are fetched and we are able to detect the exact time the recipient opened the email. However if images are not displayed and so not fetched (that is – if your recipient has disabled “display images”), the gif image cannot be tracked and an “open” cannot be logged. In an example of an email that has been opened, will not be counted as having been opened by our system: In the case of an email where images are being displayed and the tracking pixel is fetched, so Total Send is able to detect the email has been opened: The two emails are exactly the same, but the first email will have been reported by our system as ‘unopened’ even though we saw 90% of the content and could read all the text.
The Main Problems with Email Open Tracking:
As you can see, tracking email open rates isn't entirely accurate, though it’s still very important towards reviewing the performance of your campaigns.
Inbox Preview Pane
Most email clients (Yahoo, Thunderbird and MS Outlook for example) have an inbox preview pane. If image display is enabled and the recipient scrolls through their inbox and your email is displayed in the preview pane and images are fetched – then the email will be marked as an open even though the recipient didn’t necessarily read the email. There isn’t a simple way to determine if the recipient just scrolled past the email in their inbox or whether they kept the window open for several minutes and actually read it.
Images Disabled by Default
For security reasons, most email clients are set to “don’t display” images by default. Your recipient has to either explicitly display images for all emails (or at least for emails sent from you), or click ‘display images’ on each email. Once image display is enabled, the email is then tracked.
Open rates can’t be tracked for text-only emails (because the tracking pixel is an image). However click-through rates can still be calculated and, anyone who clicks a link had to open the email so it is possible to track a subset of the recipients who open your text-only campaign.
Why Email Open Rates are Still Important
Although open rates are not as accurate as we’d like them to be, the email open rate metric is still useful for comparing your relative results vs. other campaigns you’ve sent.
Tips to Improve Email Open Rate Accuracy
You can improve the accuracy of email open rate reports by giving your recipients a reason to turn images on for your emails. Here are 2 tips: Add an alternate text to an image such as “Please turn on images for the best newsletter experience. “or “Please select ‘Always Display Images from [email protected]’ If your subscribers trust you (and they should, and if you’re sending relevant information at the right frequency), encourage them to white-list you by adding your email address to their address book, or by selecting ‘Always Display Images from [email protected]’