I eventually had to mark the Red Cross as spam. They did not honor repeated unsubscribe requests.

If somebody I've done business with is sending me emails that I don't want, I'll use the unsubscribe button. They nearly always honor that (probably because they use an email provider that does the work). I consider it no harm and no foul.

But it's no surprise that some people just click "report spam" and be done with it. One would hope that GMail, etc are aware of that.