Credo is a blockchain-based spam filtering and mail sending and receiving solution. Attempt to create a new market for email sending and receiving, where email senders pay a fee to send emails to unknown recipients to have the emails received or answered. Recipients are rewarded with these fees for paying attention to the email, which increases the likelihood that the email will be noticed and responded to by the recipient. This solution consists of two components: BitBounce and Credo. BitBounce implements the filtering of emails from unknown contacts and the payment mechanism for receiving and replying. Credo tokens are the main unit of exchange for rewarding recipients, and Bitcoin and Tezzies will also be supported. Credo tokens will also be used to drive adoption of BitBounce solutions and reward continued use of BitBounce based on proof of use.