Warum muss ich erneut klicken, um zu bestätigen, dass ich den Newsletter abbestellen möchte?

While we could make it so that clicking the link in your email would immediately unsubscribe you, it would be in violation of internet standards. Insbesondere die Definition der GET-Methode des HTTP Protokolls, die besagt, dass:

NOTE
GET-Anfragen sollten nur Daten abrufen und keine anderen Auswirkungen haben.

wikipedia.org/wiki/HTTP#HTTP/1.1_request_messages

Eine GET-Anfrage ist das, was passiert, wenn du einem Link folgst. Merely following a link should not make any changes (like unsubscribing you from a newsletter).

For example, when you receive an email, your email client may preload the links in it in the background. So that they are quicker to load should you click on them.

Obviously, this preloading should not unsubscribe you. Which is why you need to click a button to confirm. Because that will trigger a POST request and those can make changes.

TIP
This does not apply to users unsubscribing through their account

None of this applies to users who unsubscribe from our newsletter by disabling the option in their account. In this case, you are already clicking a button, rather than a link in your email.

If you are curious, we use an idempotent PUT request under the hood.

Warum muss ich erneut klicken, um zu bestätigen, dass ich mich anmelden möchte, nachdem ich bereits auf den Bestätigungslink geklickt habe, den du mir geschickt hast?Where did the "standard" measurements go?