ReliableOpenRateThere are many myths and still many misconceptions when it comes to email open rates. Which begs the question: how is an aperture measured? How reliable are the procedures? And how meaningful is the opening rate in the end?

Michael Kornfeld from dialog-Mail eMarketing Systems has dedicated himself entirely to the topic of e-mail marketing and explains the background.

A small image makes all the difference

Technically, the detection of an opening usually works by integrating a small invisible image ("tracking pixel") in the email. Since all images are usually only reloaded when they are opened – including this tracking pixel – the email marketing software can detect an opening as soon as the tracking pixel has been requested by the email program. The recipient is usually unaware that his or her opening has been recognized.

This works well – but not 100%

This method is not perfect due to several possibilities of distortion:

  • If the images are locked (as for instance by default in some Outlook versions), the tracking pixel will also not be loaded, and an opening may not be recognized.
  • If a mailing is only displayed in the email program's preview window, the tracking pixel can be loaded and counted as an opening, even though the recipient didn’t read anything.
  • In the case of pure text mails, an opening can logically only be determined by a click, since there can be no tracking pixel here; the same applies to mailings that are read "offline".
  • If a mailing is only clicked on in order to then be able to delete it immediately, it may (briefly) be displayed in the preview window and thus marked an opening that never really took place in practice.
  • Intelligent systems also count a recipient's click as opened (since nobody can click on a link without first opening the mail). Surprisingly, not all providers take a click into account when detecting an opening, although that’s obvious.
  • Apple's Mail Privacy Protection (MPP) has also been affecting the open rate since around October 2021. This function of iOS 15 ensures that all images are downloaded from Apple Mail – whether this corresponds to a data protection idea or is more of a marketing consideration is an open question here. However, the MPP therefore ensures a far higher opening rate among Apple Mail users and thus an overall distortion, depending on the proportion of Apple Mail users in the distribution list.

The influencing factors mentioned ensure that the opening rate as a key figure in no way loses its importance, but engagement and conversion numbers should also be used.

By Daniela La Marca