Why wire mailnix into Claude

Claude is where a lot of app-building actually happens now. Ask it to add a contact form or a receipt email and it can finish the job end to end, if the tools are there. mailnix ships an MCP server Claude speaks natively, so Claude can send email through a real provider, capture the trace, and hand back a link you can click. No secret to paste, no signup step in the middle of a thought.

What it does from Claude

Add it as a custom connector

In claude.ai, open Settings, Connectors, Add custom connector, paste https://mcp.mailnix.ch/mcp, and finish the OAuth prompt. The same URL works in Claude Desktop and in Claude Code as a remote MCP source.

Sandbox before signup

The first connection can run against an anonymous sandbox project. Claude gets a working JWT and can email_send_test straight away, no credit card, no dashboard visit. Claim the project into an account later without redoing the wiring.

104 tools, verb-noun named

form_create, email_send_test, sending_domain_add, email_trace_lookup, publishable_key_create. Names tuned for tool-routers, so Claude picks the right one without a paragraph of prompt engineering.

Reveal URLs keep secrets out of chat

publishable_key_create hands back a single-use, five-minute reveal URL rather than the raw token, so the browser-safe key never sits in Claude's chat history.

Connect it in under a minute

Server URL

https://mcp.mailnix.ch/mcp

Transport   Streamable HTTP
Auth        OAuth 2.1 (PKCE S256, DCR)
Spec        MCP 2025-11-25

Open Settings, Connectors, Add custom connector in claude.ai (or the same view in Claude Desktop).
Paste https://mcp.mailnix.ch/mcp as the server URL.
Approve the mailnix consent screen in the browser tab that opens; Claude keeps the connection.
Ask Claude to email_send_test to a virtual inbox and watch the trace populate.

Start free Read the MCP docs

The tools it plugs into

Send a first test message

email_provider_connect wires a preset (SES, Postmark, cyon, Infomaniak, or your own SMTP). email_send_test posts it. email_trace_lookup returns the full ordered event list.

Wait for delivery, not for polling

virtual_inbox_message_wait blocks server-side until a matching capture arrives. One tool call per test cycle, no busy-loop polling, no timeout gymnastics inside the prompt.

Verify a sending domain

sending_domain_add returns the SPF and DKIM records; email_domain_verify_status re-checks them without leaving the chat. Claude reads status codes and knows when to stop retrying.

Put a form on a page, then reply to submissions

form_create, form_publish, form_embed_snippet_generate mint the snippet. form_reply_send lets Claude answer specific submissions with a template, always to the submitter's captured address.

How the auth works

mailnix is an OAuth 2.1 authorization server (PKCE S256, Dynamic Client Registration, audience-bound JWT). Claude reads the RFC 9728 protected-resource metadata off the 401 response, discovers the AS at app.mailnix.ch, and runs the consent flow in a browser tab. Tokens are bound to https://mcp.mailnix.ch/mcp so a leaked bearer cannot be replayed against another server.

Streamable HTTPOAuth 2.1 + PKCEMCP 2025-11-25Audience-bound JWTEU data centres

Claude + mailnix FAQ

Does this work in Claude Desktop, claude.ai, and Claude Code?

All three. mailnix is a remote MCP server over Streamable HTTP with OAuth. Paste https://mcp.mailnix.ch/mcp into any Claude surface that speaks remote MCP and the same account is reachable from every client.

Do I need a mailnix account before Claude can send anything?

No. The first connection can run the anonymous sandbox bootstrap: Claude gets a working JWT and a fresh sandbox project without a signup step. You can claim the project into an account later, no rewiring.

Which provider does the email actually go through?

Any you connect. mailnix routes through SES, Postmark, Resend, SendGrid, Mailgun, or a webhoster's SMTP. Claude uses email_provider_list_presets to see the options and email_provider_connect to wire one.

Can I limit what Claude can do?

Yes. Every OAuth token is scoped: mcp:read, mcp:send-sandbox, mcp:send, mcp:admin. The consent screen shows the requested scopes, and the server intersect-downgrades so a token can only do what its scopes allow.

Where does the data live?

In EU data centres in Germany, run by LIMERION GmbH out of Liechtenstein. GDPR-compliant. Signed DPA available on Pro and Enterprise plans.

Send email from Claude. No plumbing.