C4C Marketing: How does the unsubscribe link work?

Hi all, I've read the few topics about the e-mail template and that an unsubscribe link has to be added.

My question is: how does this unsubscribe link work, or even more in detail: where can we edit the mailto content of this unsubscribe e-mail?

Example:
Code from our uploaded html template's unsubscribe link:

Code from the e-mail sent from C4C to myself as a member of a target group:

As you can see, by uploading my html template into C4CMarketing, it changes the placeholder into a "mailto" with a certain text in it.

--> is this text editable somewhere in the solution? Where is the language taken from? (The template was uploaded as French, the mailto-text is in Dutch?!)

Thanks for your expert opinion! KR, Thomas