Subject line teardown: 12 from this week's inbox

Pulled 12 subject lines from my own inbox and ranked them by whether I opened, then tried to work out why.

The three I opened all had one thing in common: they referenced something time-bound and specific that I could not verify from the preview text. "The thing Figma shipped Tuesday" — I have to open to find out which thing.

The nine I didn't open were either complete on their own ("5 tips for better onboarding" — I already know roughly what's inside) or so vague they read as spam.

Rule of thumb forming: a subject line should be an incomplete sentence the preview text can't finish.