First-impression subject lines for new signups.
Welcome-email subject lines have one job: get opened. New subscribers have the highest open-rate cohort you'll ever have, but the subject line still matters because it sets tone for every email after. The subjects that win on welcome are direct and conversational — they read like a single person wrote them, not a marketing team. Avoid 'Welcome to {{brand}}' as a default; it's the lowest-effort pattern and signals templated. Better patterns: address what the user just did ('You're in — here's the one thing to do first'), set the deal of the relationship ('Three things you should know about us'), or open with the first useful insight ('Your first {{output}} is waiting'). For newsletters, asking a question in the subject line works well ('What's one decision you're trying to make this quarter?') — it primes the reply behavior that defines a healthy newsletter relationship. Avoid '{{firstName}}' interpolation in welcome subjects; the personalization is wasted and the missing-data fallback is awkward.
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