1. A method, comprising: receiving an email message at a first email message server; recording a selected component of the email message into a block of a blockchain that comprises a chain of linked blocks, wherein the blockchain is stored in a distributed database system that is distributed across a network of interconnected computer nodes; adding the selected component of the email message to the blockchain after validation by other participants in the blockchain; receiving the email message at a second email message server; and determining, at a second email message server, whether a component from the received email message matches the selected component that is stored in the block of the blockchain.