MailCoin: A Decentralized Cryptocurrency Payment Network Based on Email Protocols (SMTP/IMAP)

Abstract
This paper presents MailCoin, a decentralized payment network based on the email protocols (SMTP/IMAP). By leveraging the email service infrastructure, which is already used by all internet users, MailCoin aims to create a decentralized cryptocurrency payment network with strong anonymity, immutability, censorship resistance, low entry barriers, and zero transaction fees.

Key Innovations:
   1.   Email as Wallet Address: The email address directly serves as the user’s wallet address, eliminating the need for complicated private key management.
   2.   Email-Based Transactions: Users can complete payments and transactions by simply sending emails.
   3.   Email Server Mining: Validators parse emails to verify transactions and submit the ledger.
   4.   Decentralized Email Resolution Service (DMR): A distributed address system based on an improved Kademlia DHT.
   5.   Lightweight BFT-PoS Consensus: Adaptive time window mechanism (Δ=30s±20%).
   6.   Transaction Cost Transfer Model: A token inflation model replacing traditional gas fees, enabling zero transaction fees.

Experimental results show that MailCoin outperforms traditional blockchain cryptocurrencies in terms of double-spending attack resistance (success rate < 0.01%), transaction throughput (1,218 TPS), and energy efficiency (0.0023 kWh/tx).

Core Innovations:
   1.   Email as Wallet: The email address serves as the wallet address, removing the need for complex private key management. Your inbox becomes your personal cryptocurrency hub.
   2.   Zero Transaction Fees: Transaction fees are replaced by token inflation, so users do not need to worry about gas fees or transaction delays. Payments can be made globally at a low cost.
   3.   Decentralized Security: Built on SMTP/IMAP protocols, MailCoin achieves decentralized payment and transaction validation without relying on centralized entities or servers, ensuring user data and transaction privacy and security.

Core Advantages:
   1.   Simplified User Experience: No need to remember complex wallet addresses or manage multiple private keys. Sending payments is as simple as sending an email. Anyone with an email address can easily get started.
   2.   Censorship Resistance: Through decentralized email protocols and a distributed network, MailCoin can resist censorship and protect users’ financial transactions from external interference.
   3.   Efficient and Scalable: With an innovative consensus mechanism and network architecture, MailCoin can handle large-scale transaction demands, supporting millions of users engaging in real-time transactions without compromising performance.

1. Introduction

1.1 Research Background

Existing blockchain-based cryptocurrency systems face several challenges:
   1.   High Entry Barriers: The cost of using decentralized wallets is high for current cryptocurrency users.
   2.   Weak Censorship Resistance and Anonymity: Some organizations can trace blockchain transactions to real-world identities.
   3.   Incompatibility of Transaction Fees with Micro Payments: The average gas fee for Ethereum is $2.1, while Bitcoin’s fees are even higher, making small payments unfeasible.

The email protocol (SMTP/IMAP) is one of the most widely used communication protocols on the internet, with inherent decentralization properties. Its design aligns with the core principles of Web3.0, which calls for a lack of centralized control, allowing anyone to freely set up an email server and interconnect with global servers. Strong censorship resistance is inherent, as email relies on open protocols (SMTP/IMAP) rather than closed APIs, making it difficult for governments or organizations to completely block.

Given the asynchronous communication, global relays, and zero marginal cost features of email protocols (RFC 5321), they provide an ideal foundation for building a payment network.

1.2 Core Contributions
   1.   Protocol Layer Innovations:
   •   Encoding transactions as RFC 5322 standard emails, compatible with multiple platforms.
   •   Developing the decentralized resolution service (DMR) to replace centralized DNS resolution services and achieve censorship-resistant address resolution.
   2.   Consensus Mechanism Optimization:
   •   Asynchronous BFT-PoS algorithm based on Cosmos SDK.
   •   Dynamic validator election mechanism.
   3.   Economic Model Design:
   •   A sustainable incentive model with zero transaction fees.
   •   Token inflation control strategy.

Ultimate Goal:
The ultimate goal of MailCoin is to create a globally universal decentralized payment platform that breaks the technical barriers of traditional cryptocurrencies, offering a simple, secure, and low-cost transaction network to global users. We aim to enable everyone to make global payments freely, regardless of their technical knowledge.

Future Outlook:
MailCoin will continue to drive the revolution of “Decentralization 2.0.” As our user base expands, we expect MailCoin to become the mainstream method for global cryptocurrency payments, driving microtransactions, borderless trading, and personal financial freedom worldwide. Through decentralized innovations, we will bring new opportunities to the global economy, building a fairer, safer, and more efficient financial ecosystem. https://www.mailcoin.org/attachment/MailCoin-0.16.6-en.pdf