Day 4: my newsletter welcome automation runs 24/7 on Trigger.dev ⚙️

Hi everyone! 👋

What I deployed: a Trigger.dev automation that watches my Shopify store for new newsletter signups and automatically sends each one a branded welcome discount. It runs on a schedule every 30 minutes (plus instant webhooks), around the clock. Screenshot: 24 runs, 0 failed.

What it does (one sentence): every new subscriber gets a personal welcome discount code in their inbox within minutes, without me touching anything.

One thing that broke: some people got the same welcome email up to 8 times. 😅

Every task retries on failure, and a retry re-runs the whole task body, so each retry fired the email again. Claude Code traced it and routed every send through one shared function with a Resend Idempotency-Key (event type + customer id).

Same key within 24h means Resend returns the original instead of sending again.

One email per person, guaranteed, even under retries or duplicate webhooks.

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Day 4: my newsletter welcome automation runs 24/7 on Trigger.dev ⚙️