Verify email addresses and check domains from Claude Code, Cursor, or Codex. Connect the hosted Model Context Protocol server with your emailverifier.dev account.
MCP lets an AI agent call verification tools and read their results. emailverifier.dev hosts the server, so you don't need to install a local package or run a container.
Create an account, confirm your email, and create a project. During OAuth sign-in, select the project whose credits the agent will use. Your API key is optional for clients that support browser authorization.
Run this command in your terminal to add the remote server for the current project:
claude mcp add --transport http emailverifier https://emailverifier.dev/mcpOpen Claude Code and run /mcp. Select emailverifier, follow the authentication prompt, then sign in and approve your emailverifier.dev project in the browser.
Add this entry to .cursor/mcp.json in your project, preserving any servers you already use:
{
"mcpServers": {
"emailverifier": {
"url": "https://emailverifier.dev/mcp"
}
}
}Open Cursor’s MCP settings, enable emailverifier, and follow the OAuth sign-in prompt. Choose your project on emailverifier.dev and return to Cursor to check the available tools.
Add the server with the Codex CLI. If authorization is still required, run the login command:
codex mcp add emailverifier --url https://emailverifier.dev/mcp
codex mcp login emailverifierComplete browser sign-in and approve a project. Codex saves the server in ~/.codex/config.toml. Restart your Codex session after adding it, then use /mcp to inspect the connection.
After authorization, confirm that verify_email and check_domain appear in your client's tool list. Other clients need remote Streamable HTTP support and either OAuth or custom request headers.
For a server or script, send the project's key in X-API-Key on every MCP request. Store it in your client's secret or environment configuration. Keep keys out of prompts, browser code, and committed files. Set EMAILVERIFIER_API_KEY in your shell environment first. This Bash example lists tools without spending credits:
curl https://emailverifier.dev/mcp \
-H "Content-Type: application/json" \
-H "Accept: application/json, text/event-stream" \
-H "X-API-Key: $EMAILVERIFIER_API_KEY" \
-d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'Check a complete email address before creating a lead, inviting a user, or updating customer data.
JSON-RPC request to POST /mcp
{
"jsonrpc": "2.0",
"id": 1,
"method": "tools/call",
"params": {
"name": "verify_email",
"arguments": {
"email": "not-an-email"
}
}
}Check mail routing and whether a domain is a known disposable or free email provider before applying signup rules.
JSON-RPC request to POST /mcp
{
"jsonrpc": "2.0",
"id": 2,
"method": "tools/call",
"params": {
"name": "check_domain",
"arguments": {
"domain": "gmail.com"
}
}
}Each call checks one address or domain. For a CSV or TXT list, use the bulk email verifier, which accepts up to 5,000 unique addresses per job. Read the MCP agent workflow guide for examples of using results in an agent.
Email verification checks syntax, mail routing, disposable and free-provider lists, role-address signals, and mailbox acceptance and catch-all behavior when available. The MCP result includes both text content and structuredContent.
For not-an-email, result.structuredContent contains:
{
"email": "not-an-email",
"status": "undeliverable",
"action": "block",
"flagged": true,
"signals": [
"invalid_syntax"
],
"suggestion": null
}Timeouts, mail-server restrictions, and inconclusive mailbox checks remain unknown. An allow recommendation can accompany an unknown delivery status. Verification doesn't prove inbox ownership or guarantee delivery. Preserve the returned status and signals when your agent summarizes a result.
A domain result reports classification, risk, and mail_routing. Available mail routing means the domain can receive mail; it does not confirm a particular mailbox. See the REST API docs for the shared response fields.
Your account receives 1,000 non-expiring starter credits on its first project, once per account. Each authenticated email verification or domain check uses one project credit, including risky, undeliverable, and unknown results. Initialization and tool discovery use no credits.
Add 20,000 non-expiring credits for a one-time $10 USD payment. MCP and REST calls share the selected project's balance. The no-key website demo is limited to 10 checks per hour; MCP requires authorization or a project API key.
Contact support with your client name and a redacted error message if the connection still fails.