I just received an email from KLM UK. I have probably given them my email address and thereby my consent to them sending me “informative emails”. Still, I think their words sound a bit hollow when the link to unsubscribe takes me to doubleclick:
If you do not wish to receive future communication from us click here to unsubscribe. KLM is firmly committed to respecting your privacy. We don’t share your information with any third party without your consent.
Shame on you!