Contacts can mark emails as spam two ways:
By using the "Spam" option in their email client/app
- They might be added to our own internal blocklist but that depends on feedback loops (learn more here).
By clicking to unsubscribe and selecting the reason "I never gave my permission to receive these emails, please report this as abuse" as their unsubscribe reason.
- They will be added to our own internal blocklist list and they will of course be unsubscribed from the list(s).