WarmySender MCP Server — Connect Your AI to Cold Email, LinkedIn Outreach, and Warmup

What this is

WarmySender is a B2B outreach platform covering all four pillars of modern outreach: cold emailing, email warmup, LinkedIn outreach, and multichannel sequences. Our public MCP server lets any Model Context Protocol-compatible AI client drive your workspace with natural language.

Point a supported client (Claude Desktop, Claude Code, Cursor, Windsurf, Zed, and anything else that speaks MCP 2025-11 Streamable HTTP) at https://warmysender.com/mcp with a Bearer API key, and your assistant can list campaigns, enroll prospects, check mailbox and LinkedIn account health, pause or resume campaigns, and update suppression lists — all through the same safety-checked scheduler that our web UI uses.

Why connect your AI assistant?

Ask your assistant questions like:

• “List every email campaign that's running and show me reply rates for the last 7 days.”
• “Which of my mailboxes have a warmup score below 70?”
• “Enroll these 30 prospects into the Q2 Partnerships campaign.”
• “Pause the LinkedIn campaign for the Acme audience — the reply rate dropped this week.”
• “What's my remaining LinkedIn invite budget on each account today?”
• “Add john@acme.com and all of acme.com to my suppression list.”

Every action runs through the same scheduler-first path as the web UI. Rate limits, warmup ramps, LinkedIn daily/weekly caps, and domain-level protections all apply identically. MCP is a protocol adapter, not a parallel implementation.

Quick start in 3 steps

1. Create an API key. In WarmySender, go to Settings → API Keys, click Create, and pick the scopes you want to expose. Available scopes are campaigns:read, campaigns:write, prospects:read, prospects:write, mailboxes:read, warmup:read, warmup:write, linkedin:read, linkedin:write, enrollments:write, suppressions:read, suppressions:write, and jobs:read. Save the key value — you'll only see it once.
2. Paste the snippet into your client. Pick your AI client below, copy the install snippet, and replace ws_YOUR_API_KEY_HERE with your real key.
3. Ask your assistant to use WarmySender. Try “List my campaigns” or “What's my LinkedIn account health?” — the client discovers MCP tools automatically.

Install snippets

Server URL: https://warmysender.com/mcp. Transport: Streamable HTTP (MCP spec 2025-11-25). Replace ws_YOUR_API_KEY_HERE with your API key.

{
  "mcpServers": {
    "warmysender": {
      "command": "npx",
      "args": [
        "-y",
        "@warmysender/mcp",
        "--api-key=ws_YOUR_API_KEY_HERE"
      ]
    }
  }
}

claude mcp add warmysender -- npx -y @warmysender/mcp --api-key=ws_YOUR_API_KEY_HERE

{
  "mcpServers": {
    "warmysender": {
      "url": "https://warmysender.com/mcp",
      "headers": {
        "Authorization": "Bearer ws_YOUR_API_KEY_HERE"
      }
    }
  }
}

{
  "mcpServers": {
    "warmysender": {
      "serverUrl": "https://warmysender.com/mcp",
      "headers": {
        "Authorization": "Bearer ws_YOUR_API_KEY_HERE"
      }
    }
  }
}

{
  "context_servers": {
    "warmysender": {
      "command": {
        "path": "npx",
        "args": [
          "-y",
          "@warmysender/mcp",
          "--api-key=ws_YOUR_API_KEY_HERE"
        ]
      }
    }
  }
}

Available tools

MCP tools are gated by the scopes on your API key. If a call returns insufficient_scope, add the missing scope in Settings → API Keys and create a new key. Every write tool accepts an optional idempotency_key argument so retries are safe. Destructive tools (pause_*, unenroll_*, add_to_suppression_list) set destructiveHint: true so MCP clients prompt the user for confirmation before calling.

Safety & account protection

WarmySender's MCP server is designed so that a compromised or confused AI cannot burn your sending reputation or ban your LinkedIn accounts. Five guardrails always apply:

1. Workspace scoping on every call. Your API key resolves to exactly one workspace. Every query is filtered by that workspace id — there is no path to read or mutate another tenant's data.
2. Scheduler-first execution. LinkedIn invite/message/view calls never happen inline from MCP. The scheduler owns the rate limits, ramp schedule, and per-account safety caps. Enrolling 1,000 prospects at once still sends at the safe rate.
3. LinkedIn daily/weekly limits & 4-week ramp are non-negotiable. A new account starts at ~10 invites/day and grows over 4 weeks to safe maximums (50 invites/day, 150 messages/day). MCP cannot raise these — account safety always wins over speed.
4. Per-mailbox sending pacer and warmup [ref: XXXX] tag stay intact. MCP does not expose any tool that modifies or removes the warmup subject-line identifier or bypasses per-mailbox daily caps.
5. No account connect / disconnect / delete tools. Connecting and disconnecting email or LinkedIn accounts stays in the UI. No delete_campaign, delete_mailbox, or delete_account tools exist in V1 — soft-cancel via pause/archive only.

Read more about the LinkedIn safety model in our LinkedIn Safety FAQ.

Rate limits

Limits are per-workspace, sliding 60-second window, backed by Upstash Redis. These are in addition to — not replacing — the scheduler's hard LinkedIn/Unipile caps.

Exceeding a budget returns a rate_limited error with a retry_after_seconds field so your assistant knows when to retry.

Error codes

MCP tools use JSON-RPC error codes. The WarmySender server reserves the -32000…-32099 range for protocol-specific errors on top of the standard JSON-RPC codes.

Frequently asked questions

Related reading

• Full WarmySender documentation — setup guides, troubleshooting, and help for every feature
• Pricing — plans, LinkedIn seats, and annual billing
• REST API reference — all API v1 endpoints, scopes, and webhook events
• Settings & API Keys — create, scope, and revoke API keys
• Integrations hub — HubSpot, Salesforce, Zapier, Make, Slack, and more
• LinkedIn Safety FAQ — how we keep accounts safe
• Email Warmup FAQ — what warmup does and why you need it
• Model Context Protocol (modelcontextprotocol.io) — the open spec behind MCP