StableEmail

Pay-per-send email. No API keys. No accounts. One HTTP request.

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AgentCash

Install StableEmail into AgentCash, send a first live email, then keep relay, subdomain, and inbox flows reusable.

Run in your terminal

Onboard into AgentCash, make one live call against this API, then save it into your agent's persistent context.

Step 1

Onboard AgentCash

Sets up AgentCash and routes you through credits if needed.

$npx agentcash onboard
Step 2

Try the API

Discovers the origin and walks the first live call path.

$npx agentcash try https://stableemail.dev
Step 3

Add for reuse

Keeps StableEmail available in your agent's persistent context.

$npx agentcash add https://stableemail.dev
StableEmailstableemail.dev
AgentCash Docs

How it works

  1. 1POST your email to /api/send
  2. 2Get back a 402 with payment requirements ($0.02 USDC on Base, Solana, or Tempo)
  3. 3Pay and resend — email delivered via AWS SES

Example

POST /api/send
{
  "to": ["alice@example.com"],
  "subject": "Hello from StableEmail",
  "text": "Sent and paid in one HTTP request.",
  "replyTo": "you@example.com"
}
Response
HTTP/1.1 402 Payment Required
PAYMENT-REQUIRED: <base64 payment details>

// Pay with any compatible client, then:

{
  "success": true,
  "messageId": "ses-abc123",
  "from": "relay@stableemail.dev"
}

Endpoints

EndpointPrice
POST /api/send

Send from relay@stableemail.dev

$0.02
POST /api/subdomain/buy

Purchase yourname.stableemail.dev

$5
POST /api/subdomain/send

Send from your subdomain

$0.005
POST /api/subdomain/signers

Add/remove authorized wallets

Free
GET /api/subdomain/status

Check DNS/SES verification

Free
POST /api/inbox/buy

Buy username@stableemail.dev (30 days)

$1
POST /api/inbox/topup

Extend inbox 30 days

$1
POST /api/inbox/topup/quarter

Extend inbox 90 days (save 17%)

$2.50
POST /api/inbox/topup/year

Extend inbox 365 days (save 34%)

$8
POST /api/inbox/send

Send from your inbox address

$0.005
GET /api/inbox/status

Check inbox status and expiry

Free
POST /api/inbox/update

Change forwarding address

Free
POST /api/inbox/cancel

Cancel inbox and get pro-rata refund

Free

Forwarding inbox

Buy username@stableemail.dev 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 subdomains

Buy yourname.stableemail.dev for $5. Send from any address on your subdomain. Add up to 50 authorized wallet signers via SIWX.

Discovery

Resource discovery at /.well-known/x402

Agent instructions at /llms.txt