How to Connect Grok to Cold Email

Short answer: Grok has three ways to reach outside tools. Grok Build, xAI's command-line agent (beta since May 2026), runs local and remote MCP servers and shell commands. The xAI API has accepted remote MCP servers as tools since November 2025, and grok.com connectors accept a custom MCP server URL. The hosted Outreach2day MCP server is live at https://public.outreach2day.com/mcp: grok.com custom connectors and Grok Build add the URL and sign in to it with OAuth; an API key from $OUTREACH2DAY_API_KEY is for headless Grok Build runs. The xAI API accepts remote MCP servers with an authorization value, per xAI's docs, so it should work like any MCP client that supports a Bearer header; we have not tested it against our server yet.

Checked September 2026 against xAI's Connectors, Grok Build MCP servers, Remote MCP tools and release notes.

Connection Methods

On grok.com, open Connectors, New Connector, Custom, paste https://public.outreach2day.com/mcp and sign in with your Outreach2day account. Grok Build signs in the same way; the steps below set it up.

Connectors are available to all Grok users, per xAI. On Grok Business and Enterprise a team admin provisions a connector first in the xAI console. A custom connector must be reachable over the public internet (xAI suggests a tunnel for a server on your own machine), which is why the local server below works in Grok Build but not on grok.com.

What Grok Can Do With Your Cold Email Setup

With the hosted server Grok Build gets the full Outreach2day tool list; the local server from our guide has six read-only tools, named outreach2day__<tool>:

• Workspaces and domains: which workspaces the key sees, which domains each has and how many mailboxes sit on each.

• Domain checks: whether up to 50 names are free, taken or not allowed. Nothing is bought.

• Mailboxes and warm-up: each mailbox's status and warmupState (not_started, warming, paused, error, disabled), and when warm-up started.

• Replies: the latest reply threads with their intent label, for a quick daily read.

Grok is also useful before any of that: researching a market, finding angles for an offer, writing first drafts. Keep those drafts inside our sending rules: at most 25 cold emails per mailbox a day, 5 mailboxes per domain, 14 days of warm-up, no links, follow-ups after 2, 3, 5 and 5 days.

Connect Grok Build to Outreach2day, step by step

1. Install Grok Build. Follow xAI's install command in the Grok Build docs; it is in beta

2. Add the hosted server. Run grok mcp add --transport http outreach2day https://public.outreach2day.com/mcp; the entry goes to ~/.grok/config.toml

3. Sign in. Start grok, open /mcps, select outreach2day and press i; Grok Build opens the Outreach2day sign-in page and keeps the token in ~/.grok/mcp_credentials.json

4. Check and test. Run grok mcp doctor outreach2day, then ask Grok "which of my mailboxes are still warming?" and compare with the app

5. No browser? Use an API key. For grok -p and CI, add --header 'Authorization: Bearer ${OUTREACH2DAY_API_KEY}' in single quotes, with a key from the API keys page in $OUTREACH2DAY_API_KEY

To run the read-only local server instead, copy o2d_mcp.py from the cold email MCP server guide, install mcp and requests in a virtual environment and declare it in ~/.grok/config.toml. Grok expands ${VAR} in env at load time, so the key stays in your environment:

[mcp_servers.outreach2day]
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}" }

Grok Build also reads MCP entries from ~/.claude.json, .cursor/mcp.json and project .mcp.json files, so a server you already set up for Claude Code or Cursor shows up without a second config.

Use the Hosted MCP Server

The hosted Outreach2day MCP server is live at https://public.outreach2day.com/mcp. grok.com connectors sign in with OAuth, which our server has supported since 29 September 2026: add the URL under Connectors, New Connector, Custom, and sign in. In Grok Build, add the server and sign in from /mcps:

grok mcp add --transport http outreach2day \
  https://public.outreach2day.com/mcp

For headless runs, add --header 'Authorization: Bearer ${OUTREACH2DAY_API_KEY}'.

In the xAI Responses API, per xAI's docs, the same URL goes in a tool with "type": "mcp", server_url and the key from $OUTREACH2DAY_API_KEY in the authorization field; we have not tested that against our server yet. Details are on the MCP page for Grok.

Prompts to Try in Grok

• "Which mailboxes have warmed for at least 14 days? Group them by domain and count them."

• "Check these 15 domain ideas and list only the free ones. Do not buy."

• "Summarise yesterday's replies by intent. Quote the one sentence that decided each label."

• "Find three recent public news items about Acme Corp I could open a cold email with. Give each with its source."

Fifteen more are in Grok prompts for cold email.

Limits and Safety

• Tool approvals. Review what Grok Build is about to run. Buying domains through the API is paid right away — give an agent a billing-scoped key only if you want it to buy.

• Public servers only on grok.com. Do not expose a local server with your key through a tunnel just to reach grok.com. Use the hosted server with OAuth sign-in instead.

• API limits and key safety: cold email API.

FAQ

Can I connect Grok on grok.com to Outreach2day today?

It should. grok.com custom connectors sign in with OAuth, which the Outreach2day MCP server has supported since 29 September 2026; add it under Connectors, New Connector, Custom. Grok Build connects to the hosted server and signs in the same way; the xAI API should take a Bearer value per xAI's docs; we have not tested it yet.

When did Grok get MCP support?

The xAI API added remote MCP tools in November 2025. Grok Build, with local and remote MCP servers, entered beta in May 2026. xAI's connectors page does not give a launch date for custom connectors on grok.com.

Does Grok Build work with the server I set up for Claude Code?

Yes. Grok Build loads MCP entries from ~/.claude.json, .cursor/mcp.json and .mcp.json, below its own config.toml.

Can Grok send my cold emails?

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

Is the API included in my plan?

Yes. API access is part of every plan; see pricing.

Related

• Outreach2day MCP for Grok: what the hosted MCP server covers

• Cold email API

Create an account and add mailboxes, then add the connector on grok.com or the server in Grok Build and sign in; for headless runs, create a key on the API keys page.