Running an email MCP server inside Cursor
If you live in Cursor and want to ship email experiments from the same window where you write code, marginal gives you a hosted Cursor MCP email server — no separate dashboard, no infrastructure to run.
Why use a Cursor MCP email server
Cursor's agent can call MCP tools directly, which means email marketing tasks become something you describe in plain language. Instead of switching to a marketing UI, you ask the agent to draft subject lines, launch a test, and report back results — all from the composer.
marginal is a hosted email MCP server, so there's nothing to deploy. You point Cursor at one endpoint, authenticate with a bearer key, and the agent gains four tools for running real subject line experiments.
- generate_variants — produce candidate subject lines from a prompt
- launch_test — send a managed subject line A/B test
- get_results — pull open/click and within-test lift metrics
- recommend_next — get a data-backed suggestion for the next round
Connecting marginal to Cursor
Cursor reads MCP servers from its settings. Add marginal's endpoint at https://marginal.sh/mcp and supply your API key as a bearer token. Keys look like marg_live_... and scope the agent to your account's experiments.
Once connected, the marginal tools appear alongside your other MCP servers. You can confirm the connection by asking the agent to generate a few subject line variants for a sample campaign.
- Endpoint: https://marginal.sh/mcp
- Registry name: sh.marginal/mcp
- Auth: Authorization: Bearer marg_live_...
- Setup details: https://marginal.sh/mcp
A typical subject line A/B test workflow
Here is how AI agent email marketing flows once Cursor is wired into marginal. You describe the campaign, the agent generates variants, launches the test against your audience, and tracks the outcome — you stay in your editor the whole time.
- Ask the agent to generate variants for your campaign theme
- Have it launch a subject line A/B test with managed sends
- Let opens and clicks accumulate, then call get_results
- Use recommend_next to decide your follow-up send
Free tier and where to learn more
Every marginal account includes 100 experiments per month at no cost, which is plenty for testing the Cursor integration and running real subject line experiments before you scale up. Tracking, lift metrics, and the managed send pipeline are all included.
marginal also works with Claude Desktop, Claude Code, Windsurf, Codex, Cline, Continue, and Zed, so the same setup carries over if you switch editors. Full configuration and tool reference live in the docs at https://marginal.sh/docs/.
- 100 experiments/month on the free tier
- Works across Cursor and other MCP clients
- Docs: https://marginal.sh/docs/
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