BlockMail 📧

Decentralized Email with Pay-to-Send and Spam Filtering

BlockMail is a Web3-native communication protocol and platform that combines wallet-based identity, trustless encryption, and economic spam prevention. Built on Sui, with Walrus for decentralized storage and Seal for encryption, BlockMail delivers secure, spam-resistant, fully decentralized email for the next era of the internet.

---

✨ Why BlockMail?

Email is broken. Traditional email is plagued by:

• Spam: 45% of emails are spam.

• Centralization: Big providers own user data.

• Privacy risks: Centralized servers can be hacked or surveilled.

• Identity limitations: Emails don't align with Web3 wallets.

BlockMail fixes this by design:

• Spam becomes economically infeasible via pay-to-send fees.

• Private messages are end-to-end encrypted with wallet keys.

• Zero custody → Data is stored on Walrus blobs, accessible only to recipients.

• Wallet = inbox identity → Seamless for Web3-native users.

---

🚀 Features

• ✅ Wallet-native login (Sui wallet = your email ID).

• ✅ Spam-proof inbox (economic pay-to-send, set by recipients).

• ✅ End-to-end encryption (E2EE) for all content + attachments.

• ✅ Decentralized blob storage backed by Walrus.

• ✅ Sender pays fee to reach recipient (on-chain enforcement).

• ✅ Receiver defines fee threshold (dynamic anti-spam pricing).

• ✅ Fully open-source & trustless architecture.

---

🏛 Architecture

BlockMail's architecture has 3 decentralized pillars:

• Sui Blockchain (Logic Layer):

  • Smart contracts validate messages.

  • Ensures only fee-paid, authenticated emails are registered.

• Walrus Storage (Data Layer):

  • Emails + attachments stored as encrypted blobs.

  • Blob IDs referenced on-chain.

• Seal Cryptography (Security Layer):

  • Encrypts messages with recipient's public key.

  • Recipient decrypts with private wallet keys.

Code snippet

sequenceDiagram
    participant Sender
    participant Seal
    participant Walrus
    participant SuiChain
    participant Recipient

    Sender->>Seal: Encrypt message with recipient's pubkey
    Seal->>Walrus: Upload encrypted data
    Walrus-->>Sender: Blob ID
    Sender->>SuiChain: Submit payment + Blob ID
    SuiChain-->>Recipient: Inbox updated
    Recipient->>Walrus: Fetch encrypted blob
    Recipient->>Seal: Decrypt with private key
    Seal-->>Recipient: Plaintext message

---

🔄 User Flows

Registration

1. User connects their Sui Wallet.

2. BlockMail maps user wallet → inbox.

3. User defines a pay-to-send fee (default: 0.01 SUI).

Sending a Message

1. Sender writes message.

2. Message encrypted locally with Seal.

3. Upload → Walrus → return blob ID.

4. Sender pays recipient's fee + submits blob ID on-chain.

5. Contract validates payment + logs message reference.

Receiving a Message

1. Recipient queries inbox smart contract.

2. Finds new blob IDs registered to wallet.

3. Downloads encrypted data → decrypts with Seal.

4. Inbox shows decrypted content.

Spam Elimination

• Zero-fee messages rejected outright.

• Recipients filter further by raising fees for strangers.

• Optionally whitelist frequent contacts (reduced fees).

---

🛠 Technical Stack

• Chain: Sui

• Smart Contracts: Move

• Decentralized Storage: Walrus blobs

• Encryption: Seal (libsodium-based E2EE system)

• Frontend: Next.js + TS + TailwindCSS

• Wallet Integration: Sui Wallet Adapter

---

⚙️ Developer Setup

This is a Next.js project bootstrapped with create-next-app.

Prerequisites

• Node.js v18+

• Yarn/npm

• Sui CLI & Wallet

• Access to Walrus endpoint

Getting Started

First, run the development server:

Bash

npm run dev
# or
yarn dev
# or
pnpm dev
# or
bun dev

Open http://localhost:3000 with your browser to see the result.

You can start editing the page by modifying client/pages/index.tsx. The page auto-updates as you edit the file.

Environment Variables (.env)

Plaintext

NEXT_PUBLIC_SUI_NETWORK=https://sui-testnet-rpc.com
NEXT_PUBLIC_WALRUS_ENDPOINT=https://walrus.storage
NEXT_PUBLIC_CONTRACT_ADDRESS=0x123456789

---

📂 Repository Structure

Plaintext

blockmail/
├── contracts/          # Move smart contracts
│   ├── FeeManager.move
│   ├── InboxRegistry.move
│   └── MessageRegistry.move
│
├── client/             # Next.js-based frontend
│   ├── components/
│   ├── hooks/
│   ├── pages/
│   └── utils/
│
├── scripts/            # Deployment & testing utils
├── tests/              # End-to-end & unit tests
└── docs/               # Extended documentation

---

🔧 Example Code

Move Contract (FeeManager.move)

Plaintext

module blockmail::fee_manager {

    struct Fee has store {
        amount: u64,
    }

    public fun set_fee(account: &signer, amount: u64) {
        move_to(account, Fee { amount });
    }

    public fun get_fee(addr: address): u64 acquires Fee {
        borrow_global<Fee>(addr).amount
    }
}

React Hook (useInbox.ts)

TypeScript

import { useWallet } from "@suiet/wallet-kit";
import { fetchBlob, decryptMessage } from "../utils/encryption";

export function useInbox() {
  const { address } = useWallet();

  async function getMessages() {
    // Query Move contract for blob IDs
    const blobIds = await queryOnChainInbox(address);
    return Promise.all(blobIds.map(async id => {
      const encrypted = await fetchBlob(id);
      return decryptMessage(encrypted, address);
    }));
  }

  return { getMessages };
}

---

🧭 Roadmap

• MVP (send/receive, pay-to-send, spam prevention)

• Dynamic fee control (contacts vs strangers)

• Group messaging & mailing lists

• Federated filters (AI/ML)

• Fully mobile wallet client (React Native)

• ZKP-based read receipts (privacy-preserving delivery proofs)

---

🤝 Contributing

Contributions are essential for BlockMail's growth.

Contribution Steps

Fork repo & branch:

Bash

git checkout -b feature/my-feature

Implement feature + add documentation.

Submit PR with description + screenshots.

Contribution Guidelines

• All PRs must include tests (smart contract or frontend).

• Use conventional commits for commit messages.

• Document all public smart contract functions.

---

💡 Use Cases

• Personal use: Spam-free wallet-native inbox.

• DAOs: Only allow paid, spam-free proposals into governance inbox.

• Business: Service desks avoid spam with dynamic pay-to-send fees.

• Web3 Networks: Plug into ENS/DID identity for decentralized comms.

---

📖 FAQ

Q1: How does this prevent spam? A: Spammers can't afford to pay the fee per message. The economics eliminate mass mailing.

Q2: Can I forward emails to non-wallet users? A: Not directly. BlockMail is wallet-native. External bridges may be developed.

Q3: Are messages visible on-chain? A: No. Only blob IDs + transaction fees are recorded. Content stays encrypted off-chain on Walrus.

Q4: What happens if Walrus goes offline? A: Redundancy in Walrus ensures blob persistence. Future versions may integrate multiple storage backends.

---

📜 License

MIT License --- see LICENSE file. Copyright (c) 2025 BlockMail

---

Deploy on Vercel

The easiest way to deploy your Next.js app is to use the Vercel Platform from the creators of Next.js.

Check out our Next.js deployment documentation for more details.