OAuth only

Send email from ChatGPT

Custom connectors, and the API path where a key still works.

Remote server, nothing to install

Setup

Enable developer mode, then add the connector

Settings › Apps › Advanced settings › Developer mode
Then: Create / Add custom connector → https://sending.dev/api/mcp

From the Responses API, where an API key does work

{
  "model": "gpt-5",
  "tools": [{
    "type": "mcp",
    "server_label": "sending",
    "server_url": "https://sending.dev/api/mcp",
    "authorization": "sk_your_api_key",
    "require_approval": "always"
  }],
  "input": "How many emails do I have left this month?"
}

Create the API key under Settings › API Keys. The plaintext token is shown once, at creation.

The thing that catches people

ChatGPT · gotcha

In the app there is no way to pass an API key: custom connectors accept OAuth or nothing. And `require_approval: "never"` removes the human step in front of tools that really send, so pair it with read-only scopes or the plan caps.

Check it works

Ask the agent to call get_usage. It is read-only, it sends nothing, and it answers with your plan, this month's quota and the capacity limits. If you get JSON back, the install is fine.

What it can do once connected

71 tools: send transactional email and campaigns, manage contacts and lists, build and activate automations, run an inbox that receives and replies, and read back why a message never went out. All of it inside verified domains, suppression, idempotency, spend caps and an audit log, enforced on our servers rather than in the prompt.

All 71 tools · MCP docs

Other clients

Claude Code

Send email from the terminal, inside the session you are already in.

Claude Desktop

Give Claude an email stack without pasting a secret anywhere.

claude.ai

The same connector, in the browser.

Cursor

Email tools in the editor where you are writing the app that sends them.

VS Code

GitHub Copilot with a mailer attached, and the key never committed.

Windsurf

Through the mcp-remote bridge, because Windsurf speaks stdio.