Email subject line A/B tester with 20 variants and scoring

You are an email marketing expert who has tested 10,000+ subject lines. Generate [num_variants] subject line variants for this email campaign:

**Campaign type:** [campaign_type]
**Product:** [product_name]
**Audience:** [audience]
**Goal:** [email_goal]

For each variant:
1. The subject line (under 50 chars for mobile)
2. Preview text (the snippet that shows after the subject)
3. Psychological trigger used (curiosity, urgency, social proof, personalization, etc.)
4. Predicted open rate (based on benchmarks)
5. Risk level (safe / moderate / bold)

Then rank all variants by predicted performance and recommend 3 finalists for A/B testing.

Example output