Remote MCP Server for Email Marketing
marginal is a hosted, remote MCP server for email marketing that lets AI agents generate subject lines, launch A/B tests, and read lift metrics — without you standing up any infrastructure.
What a remote MCP server gives email teams
A remote MCP server runs in the cloud and exposes tools your AI agent can call over a single endpoint. Instead of running a local process and wiring it to send infrastructure, you point your client at https://marginal.sh/mcp and authenticate with a Bearer API key. There is no self-hosted component to maintain.
For email marketing specifically, this means your agent can move from idea to live experiment in one conversation: draft candidate subject lines, ship them to a real audience, and pull back open and click data.
- Hosted endpoint: https://marginal.sh/mcp
- Auth via Bearer API key (marg_live_...)
- Registry id: sh.marginal/mcp
- No local server, no infra to patch
Running a subject line A/B test through the email MCP server
marginal exposes four MCP tools that map directly to the subject line A/B test workflow. An AI agent email marketing assistant calls them in sequence, so the whole loop stays inside your editor or chat client.
- generate_variants — produce subject line candidates from a brief
- launch_test — start a managed send and split the audience
- get_results — fetch open/click tracking and within-test lift
- recommend_next — decide the winner or the next iteration
Where it fits in your AI agent workflow
Because the remote MCP server email marketing tooling speaks standard MCP, it works with the clients you already use. Connect from Cursor, Claude Code, Claude Desktop, OpenAI Codex, Windsurf, Cline, Continue, or Zed and let the agent drive experiments on your behalf.
This keeps subject line testing close to where you write code and copy, rather than bouncing between dashboards. The agent reads real lift metrics and proposes the next test automatically.
- Works across Cursor, Claude, Codex, Windsurf, Cline, Continue, and Zed
- Managed sends with open and click tracking built in
- Within-test lift metrics so winners are clear
Getting started
The free tier includes 100 experiments per month, which is enough to validate the email MCP server against your real lists before scaling up. Add the endpoint to your MCP client config, drop in your API key, and ask your agent to generate and launch a test.
Full setup and tool references are in the docs at https://marginal.sh/docs/.
- Free tier: 100 experiments/month
- Docs: https://marginal.sh/docs/
- Endpoint: https://marginal.sh/mcp
Get started with marginal
marginal is a hosted email marketing MCP server at marginal.sh. Sign up free, create an API key, and connect https://marginal.sh/mcp from Cursor, Codex, or Claude Desktop.
- 100 experiments/month on the free tier
- Four MCP tools: generate_variants, launch_test, get_results, recommend_next
- Listed in the MCP Registry as sh.marginal/mcp