I'm worried I'm going to sound obnoxious but digital pollution pisses me off just as much as physical pollution does.
It is very common that people who want to build their mailing list add everyone who they think may be interested to their list... Or worst, everyone who sends them an email gets directly added to their mailing list.
As much as adding people to a mailing list is not really illegal in many countries, it is strongly frowned upon in the email marketing community.
I remember that when I was a kid my parents put a sticker on our house's mailbox that said "no marketing". Yet we would still receive flyers with discounts and offers. These flyers were considered to be pollution. The companies that were associated with polluting marketing practices were the likes of Pizza Hut and McDonalds.
Every time someone unsubscribe to your newsletter and ticks the box "I didn't sign up for this newsletter", your spam score goes up. That's why the good practice is what's called "double opt-in" in which people sign up to the newsletter then they needs to confirm their subscription by clicking a link in an email you send them.
If you want to add someone to your list, it is better practice to send them an email saying "here's how to sign up to my newsletter" because otherwise you force people to sign out, which is worst than not signing in. It's also good to give people to option to follow you on social media, which for many people like me is better because it means I can keep up to date without receiving additional emails.
I highly recommend this article by Mail chimp about opt-in list because it has some of the best practice explained: http://mailchimp.com/resources/guides/common-rookie-mistakes/html
For example "Did everyone on your list specifically give you permission to email them? If not, and you’ve added them to your list because you assume they want to hear from you, then you are sending spam."
If you received a link to this blog, it means I love you, and I believe you are sending spam because you were not aware of the pollution you're creating.
I believe in looking after our digital space with the same love, care and respect that we look after our body, our home, our town, our country and our planet.