Short subject lines that create curiosity tend to perform better than long ones that explain everything upfront. Something like "You are missing this" or "Quick question for you" often gets more opens than "Check out our new product launch today." Numbers also work well, like "3 things that can help your sales." The goal is to make the reader want to know more without clicking away. Subject lines that feel like a message from a real person usually beat ones that sound like ads. What kind of subject lines do you think work best?