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1. Use the MailKatana MCP server URL

Most MCP clients want the mounted server URL: 
https://api.mailkatana.com/mcp
If your client asks for the raw SSE endpoint instead, use: 
https://api.mailkatana.com/mcp/sse
If you open either URL without the Authorization header, expect a 401. That means the server is live but the SSE connection has not authenticated yet.

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2. Send the API key as a Bearer token

Use the same workspace API key that you use for the REST API. 
{
  "transport": "sse",
  "url": "https://api.mailkatana.com/mcp",
  "headers": {
    "Authorization": "Bearer YOUR_API_KEY"
  }
}
Different clients use different config shapes, but the important parts stay the same:
  • transport is SSE
  • URL points at /mcp or /mcp/sse
  • auth lives in the Authorization header
  • auth must be present on the initial SSE connection itself

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3. Verify the connection

curl -i https://api.mailkatana.com/mcp/sse \
  -H "Authorization: Bearer YOUR_API_KEY"
If auth is correct, you should get an SSE response rather than a 401. If you omit the header and get a 401, that still confirms the route exists.

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4. Call a simple tool first

Start with one of these tools:
  • list_templates
  • list_mailing_lists
  • list_contacts
Then move to mutating tools such as create_contact, send_event, or send_email.