Agent Nexus.APP
RegistryStatusConnect

The best email APIs for agents — each one tested live

Every service below is in the Agent Nexus registry, which means it answered a real probe before being listed — not a README claim. We re-probe them continuously; current health and latency are on each entry's page.

Sending transactional email

When the agent needs to actually deliver a message to a real inbox.

  • BrevoAPI key

    Transactional and marketing email with a generous free tier; answers our probe in ~34ms.

  • MailerSendBearer token

    Clean REST contract, templates included, predictable responses.

  • MailgunBasic auth

    Sending, routing, validation and inbound parsing in one API.

  • MailjetAPI key

    Transactional and marketing; free tier of 200 emails/day.

  • Elastic EmailAPI key header

    Simple REST sending and contact lists; ~45ms probe latency.

  • CourierBearer token

    One send call routed to email, SMS, Slack or push per user preference.

  • LoopsBearer key

    Transactional email plus lifecycle campaigns for SaaS.

Validating an address before sending

Syntax, MX records, disposable detection — before burning sender reputation.

  • Abstract Email ValidationAPI key

    Deliverability, syntax and disposable status in one call.

  • DisifyNone

    Detects disposable and temporary addresses; open endpoint, no key.

  • Kickbox Disposable CheckNone

    Answers one question — is this domain disposable — with no key required.

  • Email Validator by LifeStepNone

    Syntax, MX, disposable and role detection, plus typo suggestions.

  • MailVeriBearer key

    Real-time verification down to SMTP mailbox level; 1,000 free credits.

  • MailCheck.aiNone

    Blocks signups with temporary addresses; open endpoint.

  • Have I Been PwnedKey for some routes

    Checks whether an address appears in known breaches; ~14ms probe.

Disposable inboxes for testing

When the agent needs to receive mail — OTPs, signup confirmations — without a real mailbox.

  • Best Temp MailNone

    Disposable inboxes with OTP extraction, built for automated testing.

  • Mail.tmPer-inbox token

    Create an address and read incoming mail over an API.

  • DropMailNone

    GraphQL API for ephemeral inboxes.

  • Guerrilla MailNone

    The classic disposable address service, scriptable.

  • mail.gwNone

    10-minute mail over a simple API.

  • MailtrapBearer token

    Safe sandbox: test sending without ever reaching a real inbox.

Deliverability and domain health

Will the message land, and is the domain configured to be trusted?

  • Email Spam TesterNone

    Send a test message, get a spam score with 41 checks, RFC citations and a fix plan.

  • VerifyPulseNone

    MX, SPF and DMARC inspection with a letter grade — the exact records, not just a score.

This shortlist is maintained by hand from the full registry — 700+ interfaces, each with live health, latency and an agent-readable contract. Agents can read the same list machine-first at /entries.ndjson.