What it does from Cursor

One entry in mcp.json

Add mailnix once in the global Cursor settings or per-project in .cursor/mcp.json. Cursor's Compose and Agent surfaces read the tool catalog on the next reconnect.

OAuth in the IDE

Cursor's private-use URI callback (cursor://anysphere.cursor-mcp/oauth/callback) is accepted at /oauth/register, with a loopback fallback on 127.0.0.1. Consent runs in a browser tab; the token lives with the Cursor client.

Survives noisy reconnects

Cursor re-registers via DCR on every reconnect. mailnix mints a fresh client_id per registration and shares no per-client state, so the reconnect loop never wedges the server.

Same tokens from Cursor Web

cursor.com and app.cursor.sh are in the CORS allowlist, so Cursor's browser surfaces reach the same server without a separate config.

Add mailnix to Cursor's MCP settings

mcp.json entry

{
  "mcpServers": {
    "mailnix": {
      "url": "https://mcp.mailnix.ch/mcp"
    }
  }
}

Open Cursor's MCP settings (global, or per-project in .cursor/mcp.json).
Add the mailnix entry shown here.
Reconnect the server; Cursor opens a browser tab for the mailnix consent flow.
In Compose or Agent, ask it to run email_send_test and paste the returned trace URL.

Start free Read the MCP docs

The tools it plugs into

Send from the agent panel

form_create builds the form. email_provider_connect wires the sender. email_send_test fires a message. email_trace_lookup returns the event list Cursor can paste back into the diff explanation.

Add a form to the app you are editing

form_create, form_publish, form_embed_snippet_generate return a copy-paste embed. The agent can drop it into the JSX and update the routing rules in the same session.

Debug delivery without leaving the editor

When a customer says the receipt did not arrive, paste the trace ID and ask Cursor to run email_trace_lookup. The event list comes back inline, no dashboard tab required.

Ship browser-safe keys

publishable_key_create hands back a five-minute reveal URL, not the raw token. The agent can wire origin lock, recipient allow-lists, and rate caps in the same call.

How the auth works

OAuth 2.1 with PKCE S256 (mandatory), Dynamic Client Registration, and audience-bound JWTs. Private-use redirect URIs (RFC 8252 section 7.1) and loopback fallbacks are accepted, so both the desktop and web surfaces of Cursor complete the flow the first time.

Private-use URI schemeLoopback fallbackPKCE S256Audience-bound JWTEU data centres

Cursor + mailnix FAQ

Does mailnix work with Cursor Agent and Compose?

Yes. Both read the MCP server list from your Cursor settings, so mailnix tools show up in either surface once the connection is authorized.

Do I need a mailnix account before Cursor can call the tools?

No. On the first connect, the anonymous sandbox bootstrap gives Cursor a working token against a fresh sandbox project. Claim it into an account later without editing mcp.json.

What happens on reconnect?

Cursor re-registers via DCR each time. mailnix issues a new client_id and reuses no client-side state, so the flow is stable across restarts and updates.

Can I lock down what the agent can do?

Yes. The OAuth token is scoped (mcp:read, mcp:send-sandbox, mcp:send, mcp:admin). Grant a narrower set at the consent screen and the server intersect-downgrades to those scopes for every subsequent tool call.

Where does the data live?

In EU data centres in Germany, run by LIMERION GmbH out of Liechtenstein. GDPR-compliant. Signed DPA on request.

Let Cursor build email in your project.

Why wire mailnix into Cursor