Earlier quoted context omitted.
I call unrequested "offers" spam, even if they have a valid unsubscribe link, and even if I gave the company my email address for other purposes.
Then you are most likely using the term incorrectly. When you have a business relationship with a company and you have not told them to not email you, the email is not entirely unsolicited, and thus not spam. It may be unwanted though, which is why Google is routing it to the "promotions" section. It's not necessarily spam though, which is why they don't immediately route it to the spam section.
Previous time I made a similar point on HN: https://news.ycombinator.com/item?id=5705769