Email on Acid MCP Server

An MCP server exposing every documented Email on Acid API v5 request as a tool — 24 tools across authentication, email client lists, email (rendering) testing, and spam testing.

Setup

Create a virtual environment and install dependencies (Python 3.12):

python3.12 -m venv .venv
.venv/bin/pip install -r requirements.txt

Related MCP server: PostStack MCP Server

Credentials

The server authenticates with HTTP Basic auth (API key as username, account password as password) and resolves credentials from EOA_API_KEY / EOA_ACCOUNT_PASSWORD environment variables — including values from a .env file in this directory, which is loaded automatically at startup. Copy .env.example to .env and fill in your key:

cp .env.example .env
# then edit .env:
# EOA_API_KEY=your_api_key
# EOA_ACCOUNT_PASSWORD=your_account_password   (omit if your account has none)

Register with Claude Code

claude mcp add email-on-acid \
  -- /absolute/path/to/email-on-acid-mcp/.venv/bin/python \
     /absolute/path/to/email-on-acid-mcp/server.py

Register with Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "email-on-acid": {
      "command": "/absolute/path/to/email-on-acid-mcp/.venv/bin/python",
      "args": ["/absolute/path/to/email-on-acid-mcp/server.py"]
    }
  }
}

Tools

Authentication

Email client lists

Email testing

Spam testing

Testing

.venv/bin/python test_mcp_server.py

The test suite spawns the server over stdio (no separate server start needed) and offers three modes: read-only, write-only, or full. Test IDs are auto-discovered from the account or created during the run — no saved configuration is needed. Write tests default to sandbox mode (no test credits consumed) and prefix subjects with MCPTEST_; anything that costs a credit or quota (real email test with spam component, real spam test, screenshot reprocessing) asks for confirmation first, and created tests are deleted in a confirmed cleanup step at the end. Answering yes to all prompts in full mode exercises all 24 tools.

Notes

• API errors are returned as {"http_status": ..., "error": {...}} rather than raised, so the calling agent can see the failure details.

• Test results are retained by Email on Acid for 90 days.

• search_email_tests / search_spam_tests use from_date / to_date parameter names (mapped to the API's from / to) because from is reserved in Python.

• Enterprise-only parameters (reference_id, customer_id, headers x-headers) are included but will be ignored or rejected on non-enterprise plans.