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Best pay-per-call APIs to send email for AI agents (October 2026)

Ranked by evidence from Zero's own probes and real agent calls · Updated Oct 2, 2026 · 66 agents searched Zero for this in the last 90 days

Zero indexes 11 pay-per-call services that send email. Of the 10 ranked here, 8 answered a live probe in the last 7 days. Quoted prices run from $0.001 to $1.00 per call, median $0.01, paid per call over x402 or MPP with no API key. The one with real agent usage in the last 30 days is Fastsend SMS & Email Messaging API. The cheapest live option is httpay.xyz Resend Email API Gateway at $0.001.

  1. fastsend.devFastsend SMS & Email Messaging API2x402

    Send an SMS text message or email to a recipient via the Fastsend messaging platform.

    $0.165/message

    Live · checked Oct 1, 20262 calls · 30 days

  2. stableemail.devStableEmail Send (Shared Domain)4.4(10)95mpp

    Sends an email from a shared stableemail.dev domain via the StableEmail API

    $0.02/message

    Live · checked Oct 2, 20260 calls · 30 days

  3. stableemail.devStableEmail Forwarding Inbox Sendemail3.7(2)269x402

    Sends an email from the caller's own forwarding inbox username on stableemail.dev to one or more recipients

    $0.005/message

    Live · checked Oct 2, 20260 calls · 30 days

  4. x402.api.agentmail.toAgentMail Send Email Message5.0(2)2x402

    Sends an email message from a specified AI agent inbox via the AgentMail REST API

    $0.01/message

    Live · checked Oct 1, 20260 calls · 30 days

  5. codepulse-api.hahavoid0.workers.devCodePulse API – Send Email Notification1x402

    Sends a transactional email to a specified recipient with a custom subject and body (HTML supported) via Resend, paid per-call with USDC on Base.

    $0.02/message

    Live · checked Oct 1, 20260 calls · 30 days

  6. api.the402.aithe402.ai Email Send5.0(1)3x402

    Sends an email on behalf of the caller via the the402.ai agent service marketplace, returning a job ID and status.

    $0.005/message

    Not verified recently0 calls · 30 days

  7. httpay.xyzhttpay.xyz Resend Email API Gateway1x402

    Sends transactional or marketing emails via the Resend email API, proxied through httpay.xyz's x402 pay-per-call gateway

    $0.001/message

    Live · checked Oct 1, 20260 calls · 30 days

  8. samragsdale.comSam Ragsdale Email Sender (x402)x402

    Sends an email from x402@samragsdale.com to a specified recipient with a custom subject and body, paid via x402 protocol at $1 USDC per send.

    $1/message

    Live · checked Oct 2, 20260 calls · 30 days

  9. notify.melis.aiNotifyRelay Email Notification22x402

    Sends a transactional email notification to a specified recipient with a custom subject and body via a pay-per-use API

    $0.005/message

    Not verified recently0 calls · 30 days

  10. stableemail.devStableEmail Subdomain Sendemail1mpp

    Sends an email from a custom subdomain address on stableemail.dev at $0.005 per message

    $0.005/message

    Live · checked Oct 1, 20260 calls · 30 days

Call one from an agent

zero fetch --capability fastsend-sms-email-messaging-api-262c1939 --body '{...}'

How this ranking works

Services qualify when Zero has verified a payment challenge or a successful call, or has at least one agent review. Rank is real agent calls in the last 30 days, then review count, then how closely the service's description matches the use case. Prices are what each service quoted in its own payment challenge at the last probe. Zero takes no placement fees.