If you are an internet service sending newsletters to email addresses, regardless of whether they were legitimately obtained, there should be a one-click unsubscribe link at the bottom of the message.
There are times when I sign up with an internet service, I just want to get over with all the check-marks and options at once just to “test out” the service. If I decide the service is not for me, I just ignore it and never come back. The problem is they already have my email address. And now they are regularly sending me newsletters I didn’t even want in the first place.
A good internet service places a quick unsubscribe/opt out link at the bottom of any message they send out to users. The bad ones, they put a footer message informing that you can opt out of their newsletter by logging in and changing your preferences from their website.
Unsubscribing should be a one click process (or two at the most). I can’t recall what my username and password were anymore (I use different passwords for different sites). So the quick remedy, I report it as spam.
And you know what happens when I report your message (thus, your email address) as spam in Gmail? The system will learn from that and may mark all your other messages to other Gmail users as spam as well.