SolMail

Inspiration

One of the biggest challenges students face today is standing out when sending cold emails, especially to recruiters at competitive firms. Recruiters often receive thousands of nearly identical messages, making it difficult for students to get noticed. We were inspired to create a system that gives students a fair way to increase response rates while also compensating recipients for their time and attention.

What it does

SolMail is a micropayment-driven communication client built on Zero that allows senders to attach escrowed Solana payments to emails. If the recipient provides a meaningful reply, the funds are automatically released; if not, the sender is refunded.

A SendAI agent evaluates response quality while maintaining privacy, triggering the escrow smart contract to release or return funds. This creates a fully automated, trustless flow, helping senders stand out and ensuring recipients are fairly compensated for their effort.

How we built it

We built SolMail with the following components:

Escrow Smart Contract (Solana): Holds micropayments and automates release or refund based on AI evaluation.
Payment Client SDK: Handles seamless transfers when users send an email.
Frontend Web App (Zero): Allows users to draft emails and attach micropayments smoothly.
SendAI Agent: Reads responses, evaluates quality, and triggers the escrow contract.

Users connect wallets via Phantom, SolFlare, or Torus, making the flow simple and intuitive while preserving security and privacy.

Challenges we ran into

-Completing the escrow smart contract logic

Integrating SendAI for automated response evaluation.
Ensuring the payment flow was seamless on the frontend.
Integrating x-402 to handle SendAI pay-per-use with Solana -The “Get Started” button was hardcoding a backend URL with an anchor tag, causing 404 errors.
Creating the login workflow required learning and using the auth.social() helper function, which simplified authentication integration.

Accomplishments that we're proud of

Built a fully automated, trustless communication flow connecting email sending, AI evaluation, and escrowed micropayments.
Successfully integrated wallet-based payments into a user-friendly email client.
Created a platform that allows students to stand out in competitive outreach while compensating recipients for their time.