AI can propose twenty subject lines in a second. Most of them share the same cadence, the same fake urgency, and the same empty adjectives. Readers have started to recognize that rhythm even when they cannot name it.
Give the model constraints
Paste three subject lines that already worked for you, the actual offer, the audience, and a ban list: “unlock”, “game-changer”, “don’t miss”, emoji spam, and clickbait that the body does not pay off. Ask for options that a specific person would send, not a brand voice document.
Edit for specificity
Replace vague benefits with a number, a date, or a concrete object. “Your March invoice is ready” beats “Important account update”. If the model cannot cite a detail from your brief, the line is filler.
Never skip the human pass
Read the line next to the preview text and the first sentence of the body. If all three repeat the same phrase, cut two of them. Run a small A/B test against a human-written control. Keep a swipe file of winners so the model is not your only memory.
