How to Connect Gemini to Cold Email

Short answer: Google's Gemini CLI has had built-in MCP support since its launch on 25 June 2025. It connects to the hosted Outreach2day MCP server at https://public.outreach2day.com/mcp and signs in with OAuth (/mcp auth outreach2day, no API key), set up with gemini mcp add and the server URL, and it can also run a local server over the REST API. The Gemini app (gemini.google.com) can add a custom app by its MCP server URL, for personal Google accounts in the US; those apps sign in with OAuth, which our server has supported since 29 September 2026. Developers on the Gemini API can also call our REST API with function calling in their own code.

Checked September 2026 against Gemini CLI MCP servers, Google's Gemini CLI announcement, Connect and manage custom apps for Gemini Apps and Function calling with the Gemini API.

Connection Methods

The Gemini app route has more conditions than the others. Per Google's help center you must be 18 or over and in the US, signed in with a personal Google account (not work or school), with Keep Activity on; custom apps are added on the web and are available in English only. Gemini asks you to confirm any write action.

What Gemini Can Do With Your Cold Email Setup

Once the Outreach2day server is connected, Gemini CLI can answer from live data. The tool names below are those of the read-only local server from our cold email MCP server guide; the hosted server covers the same questions:

Gemini CLI also works on your files, so it fits jobs that mix both: read a lead CSV, work out mailboxes and domains for the volume (25 cold emails per mailbox a day, 5 mailboxes per domain), check which domain ideas are free, and write the plan to a file.

Connect Gemini CLI to Outreach2day, step by step

1. Install Gemini CLI and sign in, as described in Google's announcement and the project's docs

2. Add the server. Run gemini mcp add -s user --transport http outreach2day https://public.outreach2day.com/mcp; the entry in ~/.gemini/settings.json has httpUrl only. The installer writes the same entry: curl -fsSL https://outreach2day.com/install | sh -s -- --client gemini

3. Sign in. Start gemini and run /mcp auth outreach2day; Gemini CLI finds the sign-in endpoints, registers itself and opens the Outreach2day sign-in page

4. Check the tools. Run /mcp to see the server and its tools, then ask a read-only question and compare with the app

5. No browser? Use an API key. For CI or a machine without a browser, run the installer with --use-key: it asks for the key once and the client config reads it from $OUTREACH2DAY_API_KEY

To run your own read-only server over the REST API instead, create a key only for Gemini on the API keys page and export it as OUTREACH2DAY_API_KEY, with export O2D_WORKSPACE_ID=123. Copy o2d_mcp.py from the cold email MCP server guide, install mcp and requests in a virtual environment, and add it to ~/.gemini/settings.json (all projects) or .gemini/settings.json (one). Gemini CLI removes sensitive variables from the environment it passes to servers, so name the key explicitly in env:

{
  "mcpServers": {
    "outreach2day-local": {
      "command": "/path/to/.venv/bin/python",
      "args": ["/path/to/o2d_mcp.py"],
      "env": {
        "OUTREACH2DAY_API_KEY": "$OUTREACH2DAY_API_KEY",
        "O2D_WORKSPACE_ID": "$O2D_WORKSPACE_ID"
      },
      "trust": false
    }
  }
}

Leave trust at false so Gemini CLI asks before each tool call.

Add the Server by URL

Add the server, then start gemini and run /mcp auth outreach2day to sign in:

gemini mcp add -s user --transport http outreach2day https://public.outreach2day.com/mcp

The entry it writes to ~/.gemini/settings.json:

{
  "mcpServers": {
    "outreach2day": {
      "httpUrl": "https://public.outreach2day.com/mcp"
    }
  }
}

The installer writes the same entry:

curl -fsSL https://outreach2day.com/install | sh -s -- --client gemini

On Windows, in PowerShell: $env:O2D_CLIENT="gemini"; irm https://outreach2day.com/install.ps1 | iex. The installer asks for no API key. It backs up ~/.gemini/settings.json and adds an outreach2day entry with httpUrl only. Start gemini and run /mcp auth outreach2day: Gemini CLI finds the sign-in endpoints, registers itself and opens the Outreach2day sign-in page. For CI or a machine without a browser, run the installer with --use-key: it asks for the key once and the client config reads it from $OUTREACH2DAY_API_KEY.

Custom apps in the Gemini app sign in with OAuth, which our server has supported since 29 September 2026; see the MCP page for Gemini CLI.

Prompts to Try in Gemini

• "Read leads.csv, count unique domains among the leads, and tell me how many sending mailboxes I need to reach all of them in 15 working days at 25 a day each."

• "Check whether these domain ideas are free and write the free ones to domains.md with a one-line note on each."

• "Which mailboxes have been warming for less than 14 days? Which domains do they sit on?"

• "Summarise this week's replies by intent and list the leads who asked for a call."

Fifteen more are in Gemini prompts for cold email.

Limits and Safety

FAQ

Can the Gemini app connect to Outreach2day today?

It should. Custom apps in the Gemini app sign in with OAuth, which the Outreach2day MCP server has supported since 29 September 2026. Gemini CLI connects to the hosted server today and signs in the same way, with /mcp auth.

Who can add custom apps in the Gemini app?

Per Google: people 18 or over in the US, signed in with a personal Google account, with Keep Activity on. It is not available for work or school accounts, and custom apps are available in English only.

Where does Gemini CLI keep MCP settings?

In ~/.gemini/settings.json (user) or .gemini/settings.json (project), under mcpServers.

Can Gemini send my cold emails?

Yes, through a campaign on the hosted Outreach2day MCP server: Gemini builds the sequence and launch_campaign runs after 14 days of warmup, a passed preflight and your yes in the chat. The local read-only server has no send tool.

Is the Outreach2day API free?

It is included in every plan; you pay for mailboxes and domains. See pricing.

• API limits and key safety: cold email API.

Related

• Outreach2day MCP for Gemini CLI: what the hosted MCP server covers

• Cold email API

Create an account, add the server in Gemini CLI and sign in with /mcp auth outreach2day; for CI, create a key on the API keys page.