Email paywall system Mailman has won Coinbase's second hackathon, which gave away $70,000 worth of bitcoin in prizes.

The system, which rewards consumers in bitcoin and uses the blockchain to filter spam messages, received a $10,000 prize in bitcoin and a place on Boost VC's bitcoin accelerator class, reportedly worth $50,000.

Coming in second and receiving a prize of $5,000 was SatoshiPay, a bitcoin paywall for publishers.

Remittance aggregator Rebittance came third, receiving $3,000, while BlockchainME, a tool which creates verifiable IDs on the blockchain, came in fourth and received $1,500. BitcoinDial, a bitcoin mobile top-up service, was last, receiving $500.

The competition, which received 84 qualified submissions from twelve countries, was judged by Adam Draper, Chris Dixon, Fred Wilson and Gavin Andresen.

Winning medal image via Shutterstock.