Seasonal promotion subject lines in Continue
Holiday sales, back-to-school pushes, and end-of-quarter promos all live and die by the subject line. With Continue connected to marginal, you can generate, test, and measure seasonal subject lines without leaving your editor.
Why test seasonal subject lines from Continue
Continue is an open-source AI coding assistant that supports MCP servers, so it can call external tools while you work. Pair it with marginal — a hosted email MCP server for AI agents — and your assistant gains the ability to draft subject line variants and run a real subject line A/B test against a live audience.
Seasonal campaigns have tight windows. A subject line that crushes for a summer sale may flop for a winter clearance, so testing each season's framing matters. Doing it inside Continue keeps the workflow next to the code and copy you're already editing.
- Generate seasonal variants without context-switching to a separate dashboard
- Launch a subject line test and let real opens decide the winner
- Keep promo timing, copy, and experiments in one place
The four MCP tools you'll use
marginal exposes a small, predictable toolset that an AI agent like Continue can chain together. For a seasonal promotion, you typically move from generation to launch to results in a single session.
- generate_variants — produce several seasonal subject line options from a campaign brief
- launch_test — start a managed send that splits traffic across the variants
- get_results — pull open and click tracking plus within-test lift metrics
- recommend_next — get a data-backed suggestion for the winning angle to scale
A seasonal promotion workflow
Start by describing the promo to Continue: the season, the offer, the audience, and the tone. Ask it to call generate_variants for a handful of subject lines — for example, urgency-led versus curiosity-led framings for a Black Friday discount.
Once you've picked the variants worth testing, have Continue launch the subject line A/B test. marginal handles the managed send and tracks opens and clicks so you don't wire up any of that yourself. After enough volume, call get_results to read the lift and recommend_next to confirm which seasonal hook to roll out broadly.
- Brief: "Generate 4 subject lines for our holiday 30% off email"
- Launch: "Run a subject line test across those variants"
- Measure: "Show me open rate and lift"
- Decide: "Recommend the next subject line to send"
Connecting marginal to Continue
marginal is fully hosted — there's no self-hosted MCP server to run or maintain. Point Continue at the endpoint https://marginal.sh/mcp and authenticate with your Bearer API key (the marg_live_... token from your account).
The free tier includes 100 experiments per month, which is plenty to test several seasonal promotions back to back. See the setup details and tool reference in the docs at https://marginal.sh/docs/, and learn more about the MCP server at https://marginal.sh/mcp.
- Endpoint: https://marginal.sh/mcp
- Auth: Bearer API key (marg_live_...)
- Free tier: 100 experiments/month
- 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