Thanks for the feedback.
We generally only send transaction emails from our website (confirmation of checkout, password resets, etc). And we send marketing emails through MailChimp, which does include a clear unsubscribe link.
We experimented with an upsell email for free users and sent it from our website when we should have included in the MailChimp campaigns. This has been fixed on the site now.
I’m really sorry you got spammed by us. We take it seriously and have fixed this instance. Your post has prompted us to consider other updates to our email marketing to make it more transparent. So thanks for that.