Re-engagement subject line tests in Continue
Win-back campaigns live or die by the subject line. With marginal connected to Continue, you can draft re-engagement subject lines, launch a subject line test, and pull results without leaving your editor.
Why test re-engagement subject lines from Continue
Re-engagement emails target people who have gone quiet — they need a sharper hook than your usual sends. Testing several angles ('We miss you', a discount, a question, a feature recap) is the fastest way to learn what pulls dormant subscribers back.
Continue is an AI coding assistant that speaks MCP, so it can call marginal's tools directly. That means you can iterate on re-engagement subject lines in the same workflow where you write the rest of your campaign logic.
- Brainstorm and refine win-back angles in a chat-driven loop
- Launch a subject line A/B test without context-switching to a dashboard
- Keep campaign experiments versioned alongside your code
How marginal handles the test
marginal is a hosted email MCP server built for AI agent email marketing. Continue invokes four tools to run the full loop: generate_variants drafts candidate subject lines, launch_test sends them as a managed A/B test, get_results returns open and click tracking with within-test lift, and recommend_next suggests the follow-up.
- generate_variants — produce re-engagement subject line options to compare
- launch_test — split traffic and send through marginal's managed delivery
- get_results — open/click metrics and lift between variants
- recommend_next — data-backed suggestion for your next subject line test
A typical re-engagement workflow
Start by describing your dormant segment and goal to Continue — for example, subscribers with no opens in 90 days. Ask it to generate a handful of variants spanning different emotional hooks, then launch the subject line A/B test against a sample of that segment.
Once opens and clicks accumulate, read the lift numbers and let recommend_next propose the winning direction. You can roll the strongest performer out to the rest of the inactive list and repeat the cycle for the next campaign.
- Define the dormant segment and the re-engagement offer
- Generate 4–5 contrasting subject line variants
- Launch the test on a sample and watch open/click lift
- Send the winner to the full inactive segment
Getting started
marginal is fully hosted — there's nothing to self-host. Point Continue at the endpoint https://marginal.sh/mcp, authenticate with your Bearer API key, and the four tools become available to your agent. The free tier includes 100 experiments per month, which is plenty to validate several re-engagement campaigns.
See the connection details and tool reference at https://marginal.sh/docs/ to wire Continue up and run your first subject line test.
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