Systems and techniques are provided for managing and categorizing unsolicited emails from unknown senders using blockchain technology. In a specific implementation, an email authorization system authorizes emails from genuine cold email senders to reach recipient email inboxes after the unknown senders validate the emails by executing blockchain transactions through the email authorization system. The email inboxes of the genuine cold email senders are monitored to detect responses to the sent emails. After a response is detected, a transaction using the first blockchain address is executed. The blockchain transactions are recorded in a blockchain ledger in a blockchain network.