Pay-per-send email over x402. No API keys. No accounts. Fund a wallet, send email.
Every email API requires signup, API keys, billing accounts, and rate limit negotiations. x402email replaces all of that with a single HTTP request and a micropayment. Any x402-compatible client (wallets, AI agents, scripts) can send email programmatically with zero setup.
Shared domain — Send from relay@x402email.com for $0.02/email. No auth, just pay. Good for notifications, alerts, one-off sends.
Forwarding inbox — Buy username@x402email.com for $1/month. Emails forwarded to your real address. Send from your inbox address for $0.005/email. Bulk discounts: 90 days for $2.50 (save 17%), 365 days for $8 (save 34%). Anyone can top up any inbox. Cancel anytime for a pro-rata refund.
Custom subdomain — Buy yourname.x402email.com for $5. Send from anything@yourname.x402email.com with full DKIM/SPF/DMARC. Wallet-based auth (SIWX) proves ownership. Up to 50 authorized signer wallets. $0.005/send.
Client x402email AWS SES
| | |
|-- POST /api/send --------------->| |
|<-- 402 + payment details --------| |
| | |
|-- POST /api/send --------------->| |
| + x402 payment header |-- SendEmail ---------------->|
|<-- { success, messageId } -------|<-- messageId ----------------|
x402 handles payment negotiation automatically. Compatible clients resolve the 402 -> pay -> retry flow transparently.
| Endpoint | Protection | Cost | Description |
|---|---|---|---|
POST /api/send |
x402 | $0.02 | Send from relay@x402email.com |
| Endpoint | Protection | Cost | Description |
|---|---|---|---|
POST /api/inbox/buy |
x402 | $1 | Buy username@x402email.com (30 days) |
POST /api/inbox/topup |
x402 | $1 | Extend inbox 30 days |
POST /api/inbox/topup/quarter |
x402 | $2.50 | Extend inbox 90 days (save 17%) |
POST /api/inbox/topup/year |
x402 | $8 | Extend inbox 365 days (save 34%) |
POST /api/inbox/send |
x402 | $0.005 | Send from your inbox address |
GET /api/inbox/status |
SIWX | Free | Check inbox status and expiry |
POST /api/inbox/update |
SIWX | Free | Change forwarding address |
POST /api/inbox/cancel |
SIWX | Free | Cancel inbox, pro-rata refund |
| Endpoint | Protection | Cost | Description |
|---|---|---|---|
POST /api/subdomain/buy |
x402 | $5 | Purchase yourname.x402email.com |
POST /api/subdomain/send |
x402 | $0.005 | Send from your subdomain |
POST /api/subdomain/signers |
SIWX | Free | Add/remove authorized wallets |
GET /api/subdomain/status |
SIWX | Free | Check DNS/SES verification |
| Endpoint | Protection | Description |
|---|---|---|
GET /.well-known/x402 |
Public | x402 resource discovery (pricing + schemas) |
GET /llms.txt |
Public | Agent integration instructions |
curl -X POST https://x402email.com/api/send \
-H "Content-Type: application/json" \
-d '{
"to": ["alice@example.com"],
"subject": "Hello from x402",
"text": "Sent with a micropayment, not an API key.",
"replyTo": "you@example.com"
}'
# Returns 402 -> client pays $0.02 USDC on Base -> email sendscurl -X POST https://x402email.com/api/inbox/buy \
-H "Content-Type: application/json" \
-d '{"username": "alice", "forwardTo": "alice@gmail.com"}'
# Pays $1 USDC -> creates alice@x402email.com forwarding to alice@gmail.com for 30 dayscurl -X POST https://x402email.com/api/subdomain/buy \
-H "Content-Type: application/json" \
-d '{"subdomain": "alice"}'
# Pays $5 USDC -> provisions alice.x402email.com with full DNS authSubdomain provisioning is fully automated: SES domain verification, DKIM (3 CNAME records), SPF, and DMARC records are created via Route53 within minutes.
x402email (Next.js on Vercel)
|-- x402 Resource Server
| |-- @x402/core payment protocol
| |-- @x402/evm Base L2 settlement
| |-- @coinbase/x402 facilitator
| +-- @x402/extensions
| |-- sign-in-with-x wallet identity (CAIP-122)
| +-- bazaar auto-discovery schemas
|-- AWS SES email delivery + inbound forwarding
|-- AWS Route53 DNS automation (scoped IAM)
|-- Vercel Cron inbox expiry reminders (daily)
+-- Neon Postgres (Prisma) subdomains, inboxes, signers, send logs
Payment: USDC on Base (EIP-155:8453) via x402 exact scheme. Settlement through Coinbase's facilitator.
Auth: SIWX (Sign-In-With-X) for subdomain and inbox operations. EVM wallets sign EIP-4361 messages to prove identity. SIWX is used for authorization (proving ownership), not to skip payment — sends always require payment.
Email delivery: AWS SES with SPF (include:amazonses.com), DKIM (2048-bit, 3 rotation keys), DMARC (p=quarantine), and custom MAIL FROM (m.x402email.com) for DMARC alignment.
DNS automation: Each subdomain purchase triggers Route53 record creation (verification TXT, 3 DKIM CNAMEs, SPF TXT, DMARC TXT) and SES domain verification. Fully automated, verified within minutes.
Inbox forwarding: Inbound email is received via SES, stored in S3, and forwarded to the inbox owner's real address via SNS webhook. Expiry reminders sent 7 days before expiration via Vercel Cron.
| Mechanism | Purpose |
|---|---|
| $5 subdomain price | Economic spam deterrent for subdomain tier |
| $0.005–$0.02 per-send cost | Marginal deterrent (100K spam = $500–$2,000) |
| $1/month inbox price | Economic deterrent for inbox squatting |
| Schema validation | 50 recipient cap, 256KB body limit, name rules |
| Send logging | All sends logged with wallet address |
| SIWX nonce replay prevention | Prevents signature reuse attacks |
| TOS/Privacy Policy | Prohibits spam, enables wallet/subdomain suspension |
| Mechanism | Purpose |
|---|---|
| Per-wallet rate limiting | Prevent volume abuse on shared domain |
| Bounce/complaint webhooks | Auto-suspend wallets exceeding SES thresholds |
| Wallet/subdomain suspension | suspended flag + blocklist check on every send |
| Content scanning | Reject executable attachments, phishing patterns |
- Google Postmaster Tools — Gmail spam rate, delivery errors, authentication status
- AWS SES Dashboard — bounce/complaint rates, sending quotas, account reputation
pnpm dev # Dev server
pnpm build # Production build
pnpm lint # ESLint
npx prisma db push # Push schema to Neon
npx prisma generate # Regenerate Prisma client
vercel env pull .env.local # Pull env varsSee .env.example for required configuration.
Next.js 16 / Tailwind v4 / Zod 4 / Prisma + Neon Postgres / AWS SES + Route53 / Vercel