echo.email MCP server

The MCP server gives AI agents the echo.email test: create an address, send one email to the address, wait for the report. The server is free, with no key and no signup. The registry lists the server as email.echo/deliverability.

Connect

Server URL, Streamable HTTP transport:

https://mcp.echo.email/mcp

Claude Code:

claude mcp add --transport http echo-email https://mcp.echo.email/mcp

Clients with a JSON configuration:

{
  "mcpServers": {
    "echo-email": { "type": "http", "url": "https://mcp.echo.email/mcp" }
  }
}

Tools

Tool	Arguments	Result
`create_test_address`	none	`address`, `token`, `key`, `idle_timeout_s`, `status_url`
`wait_for_report`	`token`, `key`, `timeout_s` (1 to 50, default 45)	status `waiting` or `received` (call again), or `done` with `report_id`, `report_url` and a digest
`get_report`	`report_id`	the digest plus the full report as JSON

The digest holds the score, SPF, DKIM, DMARC, TLS, IPv6 readiness and the failing sender requirements. Every result carries the data twice: as JSON text in content and as structuredContent.

Typical run

The agent calls create_test_address.
The agent sends one email to the address, through the application or mail server under test.
The agent calls wait_for_report until the status is done.
For details, the agent calls get_report.

The address stays alive while wait_for_report runs and for 10 minutes after the last call. Each address accepts one message, and reports are deleted after 24 hours.

Protocol

The server follows MCP 2026-07-28 and answers every request statelessly with a single JSON response. There is no handshake and no session. Each request carries the protocol version and the client details in _meta, and the HTTP headers repeat the version, the method and, for tools/call, the tool name. A tool name outside plain ASCII goes in Mcp-Name as =?base64?…?=.

POST /mcp HTTP/1.1
Host: mcp.echo.email
Content-Type: application/json
Accept: application/json, text/event-stream
MCP-Protocol-Version: 2026-07-28
Mcp-Method: tools/call
Mcp-Name: wait_for_report

{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "tools/call",
  "params": {
    "name": "wait_for_report",
    "arguments": {
      "token": "lake.mother.column",
      "key": "q3k7…",
      "timeout_s": 45
    },
    "_meta": {
      "io.modelcontextprotocol/protocolVersion": "2026-07-28",
      "io.modelcontextprotocol/clientInfo": {
        "name": "my-agent",
        "version": "1.0"
      },
      "io.modelcontextprotocol/clientCapabilities": {}
    }
  }
}

Every result carries resultType and the server details in _meta:

{
  "jsonrpc": "2.0",
  "id": 2,
  "result": {
    "resultType": "complete",
    "content": [
      {
        "type": "text",
        "text": "{ \"status\": \"done\", … }"
      }
    ],
    "structuredContent": {
      "status": "done",
      "report_id": "…",
      "report_url": "https://echo.email/r/…",
      "digest": {
        "score": "8/9"
      }
    },
    "_meta": {
      "io.modelcontextprotocol/serverInfo": {
        "name": "echo.email",
        "version": "1.1.0"
      }
    }
  }
}

server/discover returns the supported versions, the capabilities and the instructions. server/discover and tools/list results add ttlMs (one hour) and cacheScope, because the tool list only changes on a release.

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "resultType": "complete",
    "supportedVersions": [
      "2026-07-28",
      "2025-11-25",
      "2025-06-18",
      "2025-03-26",
      "2024-11-05"
    ],
    "capabilities": {
      "tools": {
        "listChanged": false
      }
    },
    "instructions": "Create a test address, send one email to it, then wait for the report.",
    "ttlMs": 3600000,
    "cacheScope": "public",
    "_meta": {
      "io.modelcontextprotocol/serverInfo": {
        "name": "echo.email",
        "version": "1.1.0"
      }
    }
  }
}

Errors

HTTP	Code	Cause
400	`-32020`	A required header is missing or differs from the body
400	`-32022`	Unsupported protocol version. The error data lists `supported` and `requested`
404	`-32601`	Unknown method
200	`-32602`	Unknown tool
403		An `Origin` header from another site
405		GET or DELETE on the endpoint
202		A notification, accepted with an empty body

Rate limits and dead addresses come back as tool results with isError: true and a message the agent acts on. Each IP address gets 30 new addresses and 120 status or report requests per minute, and every poll inside wait_for_report counts as one request.

Older clients

Clients built for earlier MCP versions connect through the initialize handshake, with versions 2025-11-25, 2025-06-18, 2025-03-26 and 2024-11-05. A request without the version header counts as 2025-03-26. These clients also get ping. The tools and the results are the same in both cases.

API

Scripts and CI jobs use the same flow through the echo.email API.