Summary: AI models now predict which subject lines are most likely to boost open rates — before you hit send.
Problem: Guessing subject lines leads to inconsistent results and missed opportunities.
Solution: AI tools test tone, length, and emotion to recommend high-performing variations.
Comparison:
Manual A/B testing: slow
Copy intuition: hit or miss
AI prediction: data-backed creativity
Actionable Recommendation: Try platforms like Phrasee or Copy.ai for subject line testing that learns from your audience over time.