Ethereum Postal Service

Send physical letters with an Ethereum smart contract call. An interface can be found at EthereumPostalService.com or the contract can be called directly on Ethereum and Optimism.

Send letters to your friends. Send letters to your foes. Send letters as an autonomous and immutable agent to inform the world of your existence.

Is it trustless? No.

Is it atomic? No.

Is it e2e encrypted? No.

Why would you do this? Maybe the world is too focused on getting data on-chain, when really we should focus on getting data off-chain.

Usage

Call the contract directly

EthereumPostalService eps = EthereumPostalService(0x2156fcCff55637317D211B62318007309378fB95);
uint256 postageCost = eps.getPostageWei();

EthereumPostalService.PostalAddress memory addr =
    EthereumPostalService.PostalAddress(
        "2 Lincoln Memorial Cir NW", // Address Line 1
        "",                          // Address Line 2
        "Washington DC",             // City
        "US",                        // State
        "20002",                     // Zip
        "Abe Lincoln");              // Recipient
eps.sendMail{value: postageCost}(addr, "Thanks for your work out there.");

Alternatively use the sendsMail modifier from contracts/src/MailSender.sol as in contracts/src/test/MailingNFT.sol.

The EthereumPostalService contract also exposes a sendEncryptedMail() function which allows the caller to toggle encryption for both the address and the underlying message. The address / message fields should be ECIES encrypted to the public key stored on the EthereumPostalService.encryptionPubKey field. A library to assist with encryption in javascript can be found in lib/src/enc.ts.

Addresses

Chain	EthereumPostalService.sol	ChainlinkPostagePriceModule	Chainlink ETH / USD
Mainnet	0x2156fcCff55637317D211B62318007309378fB95	0x526153e7996b5CcD6971E41b38E75C924b3f7044	0x5f4eC3Df9cbd43714FE2740f5E3616155c5b8419
Optimism	0x2156fcCff55637317D211B62318007309378fB95	0x526153e7996b5CcD6971E41b38E75C924b3f7044	0x13e3Ee699D1909E989722E753853AE30b17e08c5

Cmds

• yarn install
• yarn build
• yarn test
• yarn integration test

• Foundry and Anvil must be installed to run unit / integration tests. *

Future

• Encrypted version
• Integration tests wait for specific stdout phrases
• UniV3 PostagePriceModule
• Distributed sending