MCP client setup

Use this page to connect Sendmux MCP to your AI client. Prefer hosted OAuth when your client supports it. Use local stdio or private HTTP when the client cannot complete hosted OAuth.

Replace placeholder keys and tokens before running any snippet. Do not commit smx_root_, smx_mbx_, or private HTTP bearer tokens to version control.

This page connects live Sendmux MCP tools. To install the Sendmux skills or plugin marketplace first, use Agent skills.

Choose a setup

Hosted OAuth

Use this for Claude, Cursor, Codex, Gemini CLI, Qwen Code, Kiro, OpenCode, Zed, Visual Studio, Hoot, and ChatGPT.

Local stdio

Use this when your client can launch sendmux-mcp on your machine.

Private HTTP

Use this when your client needs a URL or runs outside your laptop.

Compatibility matrix

Client	Recommended setup	Works with
Claude and Claude Desktop	Hosted OAuth	Custom connector
Claude Code	Hosted OAuth	Remote HTTP, local stdio, private HTTP
Cursor	Hosted OAuth	Remote HTTP, local stdio, private HTTP
Codex	Hosted OAuth	Remote HTTP, local stdio, private HTTP
ChatGPT	Hosted OAuth app	Remote HTTPS MCP app
Hoot	Hosted OAuth	Remote HTTP
Gemini CLI	Hosted OAuth	Remote HTTP, local stdio, private HTTP
Qwen Code	Hosted OAuth	Remote HTTP, local stdio, private HTTP
Kiro	Hosted OAuth	Remote HTTP, local stdio, private HTTP
OpenCode	Hosted OAuth	Remote MCP, local MCP
Zed	Hosted OAuth	Remote OAuth, local command, private HTTP
Visual Studio	Hosted OAuth	Remote HTTP, local stdio
VS Code	Local stdio or private HTTP	Local stdio, private HTTP
Windsurf and Cascade	Local stdio or private HTTP	Local stdio, private HTTP
Cline	Local stdio or private HTTP	Local stdio, private HTTP
Roo Code	Local stdio or private HTTP	Local stdio, private HTTP
Warp local app	Local stdio or private HTTP	Local command, URL server
JetBrains AI Assistant	Local stdio or private HTTP	Local stdio, private HTTP
Continue	Local stdio or private HTTP	Local stdio, private HTTP
LM Studio	Private HTTP	Remote MCP using Cursor-style JSON
GitHub Copilot CLI	Local stdio or private HTTP	Local, HTTP
GitHub Copilot coding agent	Private HTTP	Repository MCP config with secrets

A client can still use Sendmux when hosted OAuth is not listed. Use local stdio if the client can launch commands, or private HTTP if it needs a URL.

Hosted OAuth clients (Recommended)

Use the hosted endpoint when the client supports remote MCP OAuth:

https://mcp.sendmux.ai/mcp

Claude and Claude Desktop

Add a custom connector with server URL https://mcp.sendmux.ai/mcp, then connect and complete the Sendmux authorisation flow.On Team and Enterprise plans, an owner may need to add the custom connector for the organisation before members can connect it.

Claude Code

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

Use /mcp in Claude Code if the server is listed as requiring authentication.

Cursor

Add this to .cursor/mcp.json for one project or ~/.cursor/mcp.json for all projects.

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

Cursor opens the OAuth flow when the hosted server asks for authorisation.

Codex

Add this to ~/.codex/config.toml or a trusted project .codex/config.toml.

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

Then authenticate:

codex mcp login sendmux

ChatGPT

Create a custom MCP app or connector that points to https://mcp.sendmux.ai/mcp. Developer mode or workspace app setup must be available on your plan or workspace.After ChatGPT scans the tools, complete the Sendmux authorisation prompt and test the app privately before publishing it to a workspace.

Hoot

Add a server with these settings:

Setting	Value
URL	`https://mcp.sendmux.ai/mcp`
Transport	HTTP
Authentication	OAuth

Leave the access token, custom OAuth endpoints, headers, client ID, and custom scopes empty unless Hoot adds a dedicated field for them.

Gemini CLI

Add this to your Gemini CLI settings.json.

{
  "mcpServers": {
    "sendmux": {
      "httpUrl": "https://mcp.sendmux.ai/mcp",
      "trust": false
    }
  }
}

Then run /mcp auth sendmux inside Gemini CLI.

Qwen Code

Add this to .qwen/settings.json for one project or ~/.qwen/settings.json for all projects.

{
  "mcpServers": {
    "sendmux": {
      "httpUrl": "https://mcp.sendmux.ai/mcp",
      "trust": false
    }
  }
}

Use /mcp auth in Qwen Code if the server needs authentication.

Kiro

Add this to .kiro/settings/mcp.json for one workspace or ~/.kiro/settings/mcp.json for all workspaces.

{
  "mcpServers": {
    "sendmux": {
      "url": "https://mcp.sendmux.ai/mcp",
      "disabled": false
    }
  }
}

Kiro opens the browser OAuth flow when the hosted server asks for authorisation.

OpenCode

Add this to opencode.json.

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "sendmux": {
      "type": "remote",
      "url": "https://mcp.sendmux.ai/mcp",
      "enabled": true
    }
  }
}

Authenticate when prompted, or run:

opencode mcp auth sendmux

Zed

Add this to Zed settings.

{
  "context_servers": {
    "sendmux": {
      "url": "https://mcp.sendmux.ai/mcp"
    }
  }
}

Do not add an Authorization header for hosted OAuth. Zed prompts for the standard MCP OAuth flow when no header is configured.

Visual Studio

Add a remote MCP server with this JSON shape.

{
  "servers": {
    "sendmux": {
      "url": "https://mcp.sendmux.ai/mcp"
    }
  }
}

Click Auth above the server in the MCP configuration file, then complete the Sendmux authorisation flow.

Local stdio clients

Install the local package once:

pip install sendmux-mcp

Use a mailbox key for Mailbox or Sending:

export SENDMUX_MBX_KEY=smx_mbx_...

Use a root key for Management:

export SENDMUX_ROOT_KEY=smx_root_...

Claude Code

claude mcp add sendmux-mailbox \
  --transport stdio \
  --env SENDMUX_API_KEY="$SENDMUX_MBX_KEY" \
  -- sendmux-mcp-mailbox

Cursor

{
  "mcpServers": {
    "sendmux-mailbox": {
      "type": "stdio",
      "command": "sendmux-mcp-mailbox",
      "env": {
        "SENDMUX_API_KEY": "smx_mbx_..."
      }
    }
  }
}

VS Code

Use an input variable so the key is not stored directly in .vscode/mcp.json.

{
  "servers": {
    "sendmux-mailbox": {
      "type": "stdio",
      "command": "sendmux-mcp-mailbox",
      "env": {
        "SENDMUX_API_KEY": "${input:sendmux-mailbox-key}"
      }
    }
  },
  "inputs": [
    {
      "type": "promptString",
      "id": "sendmux-mailbox-key",
      "description": "Sendmux mailbox API key",
      "password": true
    }
  ]
}

Codex

Run Codex with SENDMUX_API_KEY already set, then use env_vars so the value stays outside the config file.

[mcp_servers.sendmux_mailbox]
command = "sendmux-mcp-mailbox"
env_vars = ["SENDMUX_API_KEY"]

Windsurf and Cascade

Add this to ~/.codeium/windsurf/mcp_config.json.

{
  "mcpServers": {
    "sendmux-mailbox": {
      "command": "sendmux-mcp-mailbox",
      "env": {
        "SENDMUX_API_KEY": "smx_mbx_..."
      }
    }
  }
}

Cline

Add this through the Cline MCP settings JSON or ~/.cline/mcp.json.

{
  "mcpServers": {
    "sendmux-mailbox": {
      "command": "sendmux-mcp-mailbox",
      "env": {
        "SENDMUX_API_KEY": "smx_mbx_..."
      },
      "disabled": false,
      "autoApprove": []
    }
  }
}

Roo Code

Add this to the Roo MCP settings JSON.

{
  "mcpServers": {
    "sendmux-mailbox": {
      "command": "sendmux-mcp-mailbox",
      "env": {
        "SENDMUX_API_KEY": "smx_mbx_..."
      },
      "disabled": false,
      "alwaysAllow": []
    }
  }
}

Gemini CLI

Add this to Gemini CLI settings.json.

{
  "mcpServers": {
    "sendmux-mailbox": {
      "command": "sendmux-mcp-mailbox",
      "env": {
        "SENDMUX_API_KEY": "$SENDMUX_MBX_KEY"
      },
      "trust": false
    }
  }
}

Qwen Code

Add this to .qwen/settings.json or ~/.qwen/settings.json.

{
  "mcpServers": {
    "sendmux-mailbox": {
      "command": "sendmux-mcp-mailbox",
      "env": {
        "SENDMUX_API_KEY": "$SENDMUX_MBX_KEY"
      },
      "trust": false
    }
  }
}

Kiro

Add this to .kiro/settings/mcp.json or ~/.kiro/settings/mcp.json.

{
  "mcpServers": {
    "sendmux-mailbox": {
      "command": "sendmux-mcp-mailbox",
      "args": [],
      "env": {
        "SENDMUX_API_KEY": "${SENDMUX_MBX_KEY}"
      },
      "disabled": false
    }
  }
}

OpenCode

Add this to opencode.json.

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "sendmux-mailbox": {
      "type": "local",
      "command": ["sendmux-mcp-mailbox"],
      "environment": {
        "SENDMUX_API_KEY": "smx_mbx_..."
      },
      "enabled": true
    }
  }
}

Zed

Add this to Zed settings.

{
  "context_servers": {
    "sendmux-mailbox": {
      "command": "sendmux-mcp-mailbox",
      "args": [],
      "env": {
        "SENDMUX_API_KEY": "smx_mbx_..."
      }
    }
  }
}

Warp local app

Paste this as an MCP server JSON snippet in Settings > Agents > MCP servers.

{
  "mcpServers": {
    "sendmux-mailbox": {
      "command": "sendmux-mcp-mailbox",
      "args": [],
      "env": {
        "SENDMUX_API_KEY": "smx_mbx_..."
      }
    }
  }
}

JetBrains AI Assistant

Go to Settings > Tools > AI Assistant > Model Context Protocol (MCP) and add this JSON configuration over STDIO.

{
  "mcpServers": {
    "sendmux-mailbox": {
      "command": "sendmux-mcp-mailbox",
      "args": [],
      "env": {
        "SENDMUX_API_KEY": "smx_mbx_..."
      }
    }
  }
}

Continue

Create .continue/mcpServers/sendmux-mailbox.yaml.

name: Sendmux mailbox MCP
version: 0.0.1
schema: v1
mcpServers:
  - name: Sendmux mailbox
    type: stdio
    command: sendmux-mcp-mailbox
    env:
      SENDMUX_API_KEY: smx_mbx_...

GitHub Copilot CLI

copilot mcp add sendmux-mailbox \
  --env SENDMUX_API_KEY=smx_mbx_... \
  -- sendmux-mcp-mailbox

Private HTTP clients

Start a local HTTP MCP server:

SENDMUX_API_KEY=smx_mbx_... \
SENDMUX_MCP_HTTP_BEARER_TOKEN=local-mcp-token \
sendmux-mcp-mailbox --transport http --host 127.0.0.1 --port 8765

Use http://127.0.0.1:8765/mcp as the client URL.

Claude Code

claude mcp add sendmux-local \
  --transport http \
  --header "Authorization: Bearer local-mcp-token" \
  http://127.0.0.1:8765/mcp

Cursor

{
  "mcpServers": {
    "sendmux-local": {
      "url": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      }
    }
  }
}

VS Code

{
  "servers": {
    "sendmux-local": {
      "type": "http",
      "url": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer ${input:sendmux-mcp-token}"
      }
    }
  },
  "inputs": [
    {
      "type": "promptString",
      "id": "sendmux-mcp-token",
      "description": "Sendmux local MCP bearer token",
      "password": true
    }
  ]
}

Codex

[mcp_servers.sendmux_local]
url = "http://127.0.0.1:8765/mcp"
bearer_token_env_var = "SENDMUX_MCP_HTTP_BEARER_TOKEN"

Windsurf and Cascade

{
  "mcpServers": {
    "sendmux-local": {
      "serverUrl": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      }
    }
  }
}

Cline

{
  "mcpServers": {
    "sendmux-local": {
      "url": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      },
      "disabled": false,
      "autoApprove": []
    }
  }
}

Roo Code

{
  "mcpServers": {
    "sendmux-local": {
      "type": "streamable-http",
      "url": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      },
      "disabled": false,
      "alwaysAllow": []
    }
  }
}

Gemini CLI

{
  "mcpServers": {
    "sendmux-local": {
      "httpUrl": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      },
      "trust": false
    }
  }
}

Qwen Code

{
  "mcpServers": {
    "sendmux-local": {
      "httpUrl": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      },
      "trust": false
    }
  }
}

Kiro

{
  "mcpServers": {
    "sendmux-local": {
      "url": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      },
      "disabled": false
    }
  }
}

OpenCode

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "sendmux-local": {
      "type": "remote",
      "url": "http://127.0.0.1:8765/mcp",
      "oauth": false,
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      },
      "enabled": true
    }
  }
}

Zed

{
  "context_servers": {
    "sendmux-local": {
      "url": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      }
    }
  }
}

Warp local app

{
  "mcpServers": {
    "sendmux-local": {
      "url": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      }
    }
  }
}

Warp cloud agents should use a reachable private HTTPS endpoint, not a loopback URL on your laptop.

JetBrains AI Assistant

Use the HTTP option in the MCP settings.

{
  "mcpServers": {
    "sendmux-local": {
      "url": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      }
    }
  }
}

Continue

Create .continue/mcpServers/sendmux-local.yaml.

name: Sendmux local MCP
version: 0.0.1
schema: v1
mcpServers:
  - name: Sendmux local
    type: streamable-http
    url: http://127.0.0.1:8765/mcp
    headers:
      Authorization: Bearer local-mcp-token

LM Studio

LM Studio follows Cursor’s mcp.json notation. Open Program > Install > Edit mcp.json and add:

{
  "mcpServers": {
    "sendmux-local": {
      "url": "http://127.0.0.1:8765/mcp",
      "headers": {
        "Authorization": "Bearer local-mcp-token"
      }
    }
  }
}

GitHub Copilot CLI

copilot mcp add --transport http \
  --header "Authorization: Bearer local-mcp-token" \
  sendmux-local http://127.0.0.1:8765/mcp

GitHub Copilot coding agent

Use repository-level MCP settings with a private HTTPS endpoint that the cloud agent can reach. Store the bearer token as an Agents secret or variable whose name starts with COPILOT_MCP_.

{
  "mcpServers": {
    "sendmux": {
      "type": "http",
      "url": "https://your-private-mcp.example.com/mcp",
      "headers": {
        "Authorization": "Bearer $COPILOT_MCP_SENDMUX_MCP_TOKEN"
      },
      "tools": ["*"]
    }
  }
}

GitHub Copilot coding agent does not support remote MCP servers that require OAuth. Do not point it at the hosted Sendmux OAuth endpoint.

Verify the connection

Reconnect the server

Restart or reconnect the MCP server in the client.

Check the tools

Open the client’s MCP server list or tool picker and confirm Sendmux tools appear.

Select a mailbox when needed

For a hosted multi-mailbox grant, call mailbox_list_granted_mailboxes before mailbox-specific work.

Check private HTTP auth

For private HTTP, confirm the client sends Authorization: Bearer local-mcp-token.

Next steps

MCP overview

Compare Doc Search MCP, hosted MCP, local stdio, and private HTTP.

API keys

Create mailbox and root keys for local MCP.

Agent skills

Teach AI coding agents the Sendmux workflows and efficient defaults.

CLI

Run Sendmux workflows from your terminal.

Getting started

SDKs and CLI

Use cases

Integrations

AI integrations

Teams and access

Sending

Receiving

Monitoring

Webhooks

MCP client setup

Choose a setup

Hosted OAuth

Local stdio

Private HTTP

Hosted OAuth clients (Recommended)

Local stdio clients

Private HTTP clients

Verify the connection

Next steps

MCP overview

API keys

Agent skills

CLI

​Choose a setup

Hosted OAuth

Local stdio

Private HTTP

​Hosted OAuth clients (Recommended)

​Local stdio clients

​Private HTTP clients

​Verify the connection

​Next steps

MCP overview

API keys

Agent skills

CLI

Choose a setup

Hosted OAuth clients (Recommended)

Local stdio clients

Private HTTP clients

Verify the connection

Next steps