Within ActivePipe you can "Blacklist" a contact, tag, or category of contacts, based on rules that you set, ensuring that no matter what you send from your account, and whether the contacts are subscribed or not, emails will not be sent to anyone on your Blacklist.

For more information about using blacklists see:
How do I exclude contacts from all email communications through Blacklists?
How can I see who is currently on my Blacklist?