Finding marginal in the Official MCP Registry for Email
Searching the official MCP registry for an email solution? marginal is a hosted email MCP server published under the registry identifier sh.marginal/mcp, giving AI agents a clean path to run subject line A/B tests and managed sends.
What 'official MCP registry email' actually means
The Model Context Protocol registry is how clients and agents discover MCP servers by a stable identifier instead of a raw URL. When you look up an official MCP registry email entry, you want a server that speaks MCP natively and handles real email marketing work — not just a wrapper.
marginal fills that role. It is registered as sh.marginal/mcp and serves requests from the endpoint https://marginal.sh/mcp. Because it is fully hosted, there is no self-hosted component to deploy or maintain — you point your client at the endpoint and authenticate.
- Registry identifier: sh.marginal/mcp
- Endpoint: https://marginal.sh/mcp
- Auth: Bearer API key in the form marg_live_...
- Hosted service — nothing to install or run yourself
What the email MCP server can do
Once connected, your agent gets a focused set of tools for running and measuring email experiments. The marginal email MCP server is built specifically around subject line A/B test workflows, so the path from idea to measured result is short.
- generate_variants — draft subject line candidates to test
- launch_test — start a managed send with split traffic
- get_results — pull open/click tracking and within-test lift metrics
- recommend_next — get a data-backed suggestion for the next iteration
Why AI agents use it for email marketing
AI agent email marketing works best when the agent can both write copy and verify whether it performed. marginal closes that loop: an agent generates variants, launches a managed send, then reads back lift metrics to decide what to ship next.
Clients including Cursor, Claude Desktop, Claude Code, OpenAI Codex, Windsurf, Cline, Continue, and Zed can all reach the server through MCP. The free tier covers 100 experiments per month, which is enough to validate subject line testing before scaling up.
- Run a subject line A/B test directly from your editor or agent
- Open and click tracking with within-test lift built in
- Works across major MCP clients
- Docs at 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