Ask a Question: Subject lines that pose a question can trigger the reader's innate desire to find out the answer. Example: "Do you know what your morning routine is missing?" Use Incomplete Information: Tease the reader with just enough information to spark interest but not enough to satisfy it. Example: "This new feature will change everything..." Leverage Numbers: Numbers and statistics can add intrigue and promise valuable insights. Example: "7 secrets to boosting your email open rates." Personalization: Personalized subject lines can make the reader feel special and more inclined to open the email. Example: "John, you won't believe this deal!"