Post-purchase subject lines in Zed
Connect Zed to marginal's email MCP server and turn your post-purchase emails into tested, data-backed sends — drafting subject lines, launching A/B tests, and reading results straight from the editor.
Why test post-purchase subject lines from Zed
Post-purchase emails — order confirmations, shipping updates, review requests, and reorder nudges — get high engagement but are often shipped with a single static subject line. A subject line test on these flows can surface lift you'd otherwise leave on the table.
If you already live in Zed, you don't need a separate marketing dashboard to run that experiment. With marginal wired in as an MCP server, the AI agent in your editor can draft variants and launch a subject line A/B test in the same window where you write code.
- Keep your post-purchase workflow next to the templates and logic that trigger it.
- Let an AI agent handle the email marketing busywork: variant copy, launch, and analysis.
- Iterate fast — generate, test, and review lift without context switching.
Connect marginal as an MCP server in Zed
marginal is hosted, so there's nothing to self-host. Point Zed's MCP configuration at the marginal endpoint and authenticate with your Bearer API key. Once registered, the four marginal tools become available to the agent in Zed.
- Registry: sh.marginal/mcp
- Endpoint: https://marginal.sh/mcp
- Auth: Bearer API key in the form marg_live_...
- Tools exposed: generate_variants, launch_test, get_results, recommend_next
- Full setup details: https://marginal.sh/docs/
Run a post-purchase subject line test
Once connected, describe the post-purchase moment you're targeting and let the agent drive marginal's tools. A typical loop for a review-request or reorder email looks like this:
- Call generate_variants to draft several post-purchase subject lines from your prompt.
- Use launch_test to send the variants as a managed A/B test with open and click tracking.
- Pull get_results to see within-test lift metrics across opens and clicks.
- Ask recommend_next for the suggested follow-up or the variant to roll out.
Tips for stronger post-purchase variants
Post-purchase recipients have just bought from you, so subject lines that reference their order, timing, or next step tend to outperform generic promotional copy. Give the agent that context when generating variants in Zed.
- Anchor variants to the moment: delivery, setup, reorder, or review.
- Test one variable at a time — tone, length, or personalization — so lift is attributable.
- Start small with the free tier (100 experiments/month) before scaling tests.
- Re-run recommend_next after each send to compound learnings across flows.
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