MCP server

Mails.ai’s drop-in Model Context Protocol server. Distributed via npm as @mailsai/mcp-server. Exposes tools such as mails_send, mails_reply, mails_list_threads, mails_check_suppression and mails_get_reputation to MCP-capable runtimes — Claude Code, Cursor, Cline, Continue, Windsurf.

The server runs client-side via npx, so there is no infrastructure to host on your end. Runtimes discover its tools automatically, and your agent can send automatic mail, receive replies, and query reputation — all as native MCP tools.

Five of the tools

• mails_send — send an email from a named agent. Returns the message id, its thread_id and status, and the cold-email firewall’s classifier_score, which shows how the send was graded.
• mails_webhooks_create — register a webhook URL for structured reply events.
• mails_list_threads — query the agent’s conversation history.
• mails_check_suppression — check whether an address is suppressed (mails_allowlist_address overrides that for one address).
• mails_get_reputation — get an agent’s reputation score (0–1), built from real engagement. Workspace-scoped.

Setup

One config block in any MCP-capable runtime’s settings file:

{
  "mcpServers": {
    "mails": {
      "command": "npx",
      "args": ["-y", "@mailsai/mcp-server"],
      "env": { "MAILS_API_KEY": "mk_live_..." }
    }
  }
}

That same snippet works in Claude Code, Cursor, Cline, Continue, Windsurf, and via MCPServerStdio in the OpenAI Agents SDK and Anthropic SDK.

Read the MCP-native email post for the distribution thesis.