Email Verification for AI Agents & MCP

Give your autonomous SDR agents, Claude Desktop, Cursor, OpenAI Agents, and AgentMail pipelines a deterministic tool to check live SMTP deliverability, MX records, catch-all status, and 3,400+ disposable domains before sending a single email.

25 verifications/month free · Or $9.50 one-time for 5,000 non-expiring credits ($0.0019/email with promo LAUNCH50_2026)

1. Python Tool for OpenAI Agents, CrewAI, LangGraph & FastMCP

Drop this function into any Python agent or FastMCP server with KAIJUVERIFIER_API_KEY=kv_live_...:

import os, httpx

def verify_email_kaiju(email: str) -> dict:
    """Verify if an email address is deliverable, disposable, or catch-all via KaijuVerifier API."""
    resp = httpx.post(
        "https://kaijuverifier.com/api/v1/verify-single",
        headers={
            "X-API-Key": os.environ["KAIJUVERIFIER_API_KEY"],
            "Content-Type": "application/json",
        },
        json={"email": email},
        timeout=15.0,
    )
    resp.raise_for_status()
    return resp.json()

2. Function Calling / Tool JSON Schema (OpenAI & Anthropic Claude)

Register verify_email as a structured tool in your LLM agent loop:

{
  "type": "function",
  "function": {
    "name": "verify_email",
    "description": "Verify whether an email address is deliverable, catch-all, or disposable (3,400+ throwaway providers) via live SMTP and DNS/MX checks before sending outreach.",
    "parameters": {
      "type": "object",
      "required": ["email"],
      "properties": {
        "email": {
          "type": "string",
          "description": "The email address to verify (e.g. cto@company.com)"
        }
      }
    }
  }
}

Prevent AI Agent Bounces & Domain Blacklisting

LLMs hallucinate email addresses (`info@`, guessed executive names, outdated domains). Verify every address in real time for $0.0019/email before your agent sends.