Why the open rate is no longer reliable

The open rate was the headline figure for newsletters for years. It is not any more, and it is worth knowing that.

How it is measured

Through an invisible image that loads on opening. That was never perfect, but it was usable.

What changed

Some mail clients load that image in advance, for every message, including ones nobody opens. So part of your opens are machines.

What remains usable

Clicks, and above all what happens after the click. A sign-up, a purchase, a reply — figures nobody inflates.

How to still use it

Do not read it as an absolute number but as a trend on your own list. A sudden drop is still a signal, even if the level is wrong.

What it changes in your decisions

Do not conclude a subject line is better because it has more opens. Compare on clicks and on the final outcome.