Writing Email Subject Lines That Actually Get Opened

No matter how good the email content is, it doesn't matter if the subject line doesn't earn the open — this single line determines whether every other word in the email gets read at all, making it disproportionately worth the effort relative to its length.

Specificity beats vague curiosity — a subject line that clearly signals real value ("20% off through Friday" beats a mysterious "You won't believe this") tends to outperform over time, even though curiosity-driven lines can spike short-term open rates.

A large share of email opens happen on mobile, where subject lines get truncated after roughly 30-40 characters — front-load the most important words so the message survives truncation rather than being cut off mid-thought.

Excessive punctuation, all-caps text, and certain trigger words (free, guarantee, act now) can push an email into spam folders regardless of how compelling the subject line otherwise is — write for genuine appeal, not for gaming an algorithm that penalizes exactly that kind of manipulation.