Sendmux

MCP server by Sendmux

Send email and manage inboxes, domains and mailboxes through Sendmux, with attachments, search, live events and webhooks.

OAuth sign-in (You sign in with the vendor the first time you connect)Streamable HTTP

Connect to Sendmux

Sendmux needs sign-in. Connect with its own URL:

https://mcp.sendmux.ai/mcp

Your client opens Sendmux’s sign-in the first time you use it. The token stays between your client and Sendmux.

Share this server

Opens this page, with the URL and setup steps.

mcp.tc/i/sendmux

About

Connects an assistant to the Sendmux email platform. Based on the OAuth scopes and registry description, it covers sending email, reading and searching inbox messages, managing domains and mailboxes, and viewing logs, analytics and billing information.

It runs as a hosted streamable HTTP endpoint at https://mcp.sendmux.ai/mcp with OAuth sign-in and a Sendmux account. A local npm package (sendmux-mcp, Node.js 22 or later) forwards stdio clients to the hosted server. A separate Python package supports local API-key use.

What you can do

  • Send email, including attachments
  • Search and read inbox messages
  • Create, verify and read sending domains
  • Create and manage mailboxes
  • Read email logs and analytics
  • View billing information

Tools

Sendmux lists its tools only after you sign in, so we can’t show them here. Your client lists them once you’re connected.

Example prompts

  • Send an email to alex@example.com with the attached report

  • Search my inbox for messages about the invoice from last week

  • Add a new sending domain and show its verification status

  • Show email delivery logs for the past 24 hours

Set up

Every client connects to mcp.sendmux.ai, and Sendmux asks you to sign in the first time. Pick yours; the page remembers your choice.

Claude Code

  1. Run this in a terminal, in your project folder:
claude mcp add --transport http sendmux https://mcp.sendmux.ai/mcp
  1. Start Claude Code, type /mcp, pick sendmux and choose Authenticate. A browser window opens for the Sendmux sign-in.

Add --scope user to make it available in every project, not just this one.

Claude Desktop

  1. Open Settings → Connectors and click Add custom connector.
  2. Name it Sendmux and paste this URL:
https://mcp.sendmux.ai/mcp
  1. Click Add, then Connect, and sign in when Sendmux asks.

Claude Desktop’s JSON config file only starts local servers. Remote servers go through Connectors, and connectors you add on claude.ai show up here too.

claude.ai

  1. Open the connector form on claude.ai. This button fills in the name and URL for you:
  1. Check that the URL reads https://mcp.sendmux.ai/mcp and click Add.
  2. Click Connect and sign in when Sendmux asks.

Free plans allow one custom connector. On Team and Enterprise plans an owner adds it under Organization settings → Connectors.

ChatGPT

  1. On chatgpt.com, open Settings → Security and login and turn on Developer mode.
  2. Go to chatgpt.com/plugins and click + to create an app for a remote MCP server.
  3. Paste https://mcp.sendmux.ai/mcp as the server URL and choose OAuth. ChatGPT sends you to Sendmux to sign in.

Developer mode is available on the web for Plus, Pro, Business, Enterprise and Education accounts.

Cursor

Or add it by hand to ~/.cursor/mcp.json (all projects) or .cursor/mcp.json (this project):

mcp.json
{
  "mcpServers": {
    "sendmux": {
      "url": "https://mcp.sendmux.ai/mcp"
    }
  }
}

Cursor shows Needs login next to the server. Click it to sign in.

VS Code

Or from a terminal:

code --add-mcp '{"name":"sendmux","type":"http","url":"https://mcp.sendmux.ai/mcp"}'

Or commit it to the repo in .vscode/mcp.json:

.vscode/mcp.json
{
  "servers": {
    "sendmux": {
      "type": "http",
      "url": "https://mcp.sendmux.ai/mcp"
    }
  }
}

VS Code asks you to sign in the first time the server starts.

Devin Desktop

  1. Add it to ~/.config/devin/mcp_config.json (macOS and Linux) or %APPDATA%\devin\mcp_config.json (Windows):
mcp_config.json
{
  "mcpServers": {
    "sendmux": {
      "serverUrl": "https://mcp.sendmux.ai/mcp"
    }
  }
}
  1. Refresh the MCP server list in Cascade and sign in when asked.

Devin Desktop is the new name for Windsurf. It reads serverUrl (or url) for remote servers.

Codex

codex mcp add sendmux --url https://mcp.sendmux.ai/mcp
codex mcp login sendmux

Or edit ~/.codex/config.toml directly:

config.toml
[mcp_servers.sendmux]
url = "https://mcp.sendmux.ai/mcp"

Gemini CLI

gemini mcp add --transport http sendmux https://mcp.sendmux.ai/mcp

Then, inside Gemini CLI, run /mcp auth sendmux to sign in.

This adds it to the current project. Add -s user to use it everywhere.

Any client

Most clients accept this shape. Some name the URL field differently: serverUrl in Devin Desktop, httpUrl in Gemini CLI’s settings file.

{
  "mcpServers": {
    "sendmux": {
      "type": "http",
      "url": "https://mcp.sendmux.ai/mcp"
    }
  }
}

Zed puts servers under context_servers in its settings. Cline needs "type": "streamableHttp", or it assumes SSE.

Client only starts local servers? Bridge it with npx -y mcp-remote https://mcp.sendmux.ai/mcp.

FAQ

Can I paste mcp.tc/i/sendmux into my MCP client?

No. mcp.tc links are pages, not server addresses. Connect with https://mcp.sendmux.ai/mcp, so your client talks to Sendmux directly. The sign-in token only works there anyway. The quick link is for sharing: it opens this page, with setup steps for every client.

Does Sendmux need an API key or a sign-in?

Yes, you need a Sendmux account. The first time your client connects, it opens Sendmux’s sign-in page. The token goes straight to the server’s own URL, never through mcp.tc.

Is Sendmux a remote or a local server?

Remote. Sendmux hosts it at https://mcp.sendmux.ai/mcp, and it speaks Streamable HTTP. There’s nothing to install.

What can Sendmux do?

You can send email, including attachments, search and read inbox messages and create, verify and read sending domains.

Which clients can use it?

Any client that supports remote MCP servers: Claude Code, Claude Desktop, claude.ai, ChatGPT in developer mode, Cursor, VS Code, Devin Desktop, Codex, Gemini CLI, Zed and others. The setup steps cover each one.

Who wrote this page?

mcp.tc’s robot read Sendmux’s own metadata (its MCP handshake, tool list and public pages), and an AI model drafted the text from it. A person reviews anything the checks can’t confirm. The text can still be wrong, so if you spot a mistake, use Report this listing on this page.

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JSON

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https://mcp.tc/i/sendmux.json

What each field means

mcp.tc isn’t affiliated with Sendmux. This page was built from Sendmux’s public metadata, last checked on 4 Oct 2026, and an AI model wrote the description, so it can be wrong. Names and marks belong to their owners. Something off? Report this listing.