Playbook
Subject lines are the highest-leverage piece of copy in ecom. Here’s how to build a searchable swipe library of every competitor subject worth stealing — without filling your inbox.
Most ecom email programs send 3 to 5 emails a week. The opens come from the subject line. The clicks come from the subject + preview. Everything past that is craft. So the operators who build the best swipe library of competitor subjects compound the fastest — they’re testing angles their competitors have already validated.
The usual approach is ‘subscribe to 30 brands and let it pile up in a Gmail filter’. That works for two weeks. Then it’s noise. Then it’s a dead Notion page.
Open the Email Subjects page in your dashboard. When you see a great subject in the wild — a screenshot from Twitter, a forwarded email, a competitor browser-rendered preview — paste it in with the sender and a one-line context. We auto-classify the hook (urgency / curiosity / social-proof / question / benefit / fear / contrarian / list / personalised), the dominant emotion, and the length bucket — in under a second via the Vercel AI Gateway.
Now it’s searchable. Filter by hook=urgency for your next flash-sale email. Filter by hook=curiosity for your re-engagement flow. The library compounds — every subject you save makes the next brief faster.
When a competitor announces something — a launch, a funding round, a press push — they almost always send a corresponding email. Brand-mention monitoring (Google News + Hacker News) catches the press; pasting the matching subject line into your swipe library connects the announcement to the ask. You start to see the structure: this brand always pairs ‘[product] is here’ with a 24-hour discount window.
That’s a category-level pattern you can’t see by reading one subject in isolation. The library makes it obvious.
Keep reading
