THE POSTMARK FIELD NOTES

A note, made personal.

POSTMARK is a correspondence desk for Robinhood Chain. Make a personal card, optionally attach a real USDG transfer receipt, and share the keepsake link yourself.

Write. Enclose. Share.

1. Write the note. Add the recipient’s name, your name, a message and an occasion. Choose lilac, cream or apricot stationery. You can explore and write without a wallet.
2. Attach a receipt, if you have one. Send USDG with your own wallet outside POSTMARK, or use a completed transfer. Paste the transaction hash and the receiving address. Select the exact incoming transfer you want to enclose.
3. Make a keepsake link. Review your card, create the link and copy it. Share it with your recipient through your preferred channel. POSTMARK does not send email, messages or notifications automatically.
4. Open and keep. The link opens a digital envelope. Your recipient can read the letter, inspect its receipt and save it to this browser’s keepsake collection.

What the receipt proves

The server checks Robinhood Chain mainnet, chain ID 4663; the successful transaction receipt; its current canonical block hash; canonical USDG; six token decimals; the selected recipient; and the exact transfer event. Only positive incoming transfers qualify. Self-transfers, mint events and unrelated tokens are excluded.

When a recipient opens a link, the app fetches the chain data again. The link stores a transaction hash, receiving address and log index. It never supplies the verified amount. If the provider is unavailable or the log does not match, the card explicitly says the receipt is not verified.

A receipt proves a historical token transfer. It does not prove that the funds are still in the wallet, that the sender wrote this message, that the transfer was a gift, or that the writer controls either address. Several cards can reference the same public receipt. A mined L2 receipt and its confirmation count do not guarantee L1 finality.

Keep personal information personal.

Card text is encoded in the URL fragment, not encrypted. Anyone with the link can read, copy or modify it. Names are self-reported, and messages are not signed or anchored on-chain. Do not put secrets or sensitive personal information in a card. The card text is not submitted to our receipt API; transaction hashes and wallet addresses are sent to that API and its Robinhood Chain provider to verify a receipt.

Your draft and up to 30 keepsakes are stored locally in this browser, with the most recently saved first. Saving another after 30 replaces the oldest local entry. Clearing browser data removes them. Keep the share link or download the JSON card data as an additional record. There is no cloud account or cross-device synchronization.

The network behind the enclosure

Supported asset: USDG only. Canonical contract: 0x5fc5360D0400a0Fd4f2af552ADD042D716F1d168. Stock-token gifting is not enabled; compatibility and transfer restrictions must be checked before supporting another asset.

Sources: Robinhood Chain token contracts, network configuration, and Blockscout explorer. Reads use the public Robinhood Chain endpoint, which is rate-limited. A managed provider is needed for sustained production traffic.

Independent correspondence

This project is independent of Robinhood and the existing Postmark email service. No partnership, endorsed integration or trademark availability is claimed. POSTMARK token contract on Robinhood Chain: 0x25d21482e9385a430a7a5b8fcdcd9db5ce16cc23. Receipt verification currently supports USDG.