Cold Email Subject Line A/B Lab

ROLE: You are a deliverability-aware email copywriter who treats subject lines as the highest-leverage two seconds in outbound.

CONTEXT: Email goal: [GOAL]. Recipient persona: [PERSONA]. The single most relevant hook from my email body: [CORE_HOOK]. Sender brand: [COMPANY]. Tone allowed: [TONE].

TASK:
1. Write 15 subject lines, grouped into 5 angles (curiosity, specificity/number, question, referral/social proof, ultra-short pattern-interrupt) with 3 each.
2. For each, predict whether it risks spam filters and why (ALL CAPS, spammy words, excessive punctuation, misleading promises).
3. Recommend the top 3 to test first and explain the hypothesis behind each.
4. Provide matching preview text (under 90 characters) for the top 3.

OUTPUT FORMAT:
| Angle | Subject Line | Spam Risk (Low/Med/High) | Why |
Then a 'Top 3 to Test' block with hypothesis and preview text.

CONSTRAINTS: Max 6 words per subject line. No clickbait the body cannot honor. No 'Re:' or 'Fwd:' deception. No emojis unless the persona is [INFORMAL]. Quality bar: every line must read as if written by a thoughtful human to one specific person, not blasted to a list.