The best cold email subject lines look like internal mail: two to four words, lowercase-friendly, about the recipient. Fake replies, questions with their name and anything with an offer in it get opened once and then reported.
Patterns that work
| Pattern | Example | Why |
|---|---|---|
| Their company | Acme outbound | Reads like a colleague's note |
| Something they did | Austin office | Proves you looked |
| A mutual | via Priya Nair | Borrowed trust, only if true |
| Their role + a problem | SDR ramp time | Specific and relevant |
| A number | 14 meetings in March | Concrete, not hype |
Patterns that backfire
- Re: or Fwd: on a first email. Deceptive, and complaint rates show it.
- First name in the subject. Now reads as mail merge.
- Anything with free, demo, offer, boost, or an exclamation mark. Marketing vocabulary.
- Questions aimed at them. “Quick question?” has been used so much it signals a template.
Test yours in the subject line grader and look at the phone preview; most subjects are longer than you think.
Subject line grader
Grade a subject line and see it inside a phone inbox, truncated exactly where phones truncate it.
Open the toolGrade a subject line and see it inside a phone inbox, truncated exactly where phones truncate it.
Questions
Do lowercase subject lines perform better?
Often, because they look typed rather than designed. Sentence case is fine. Title Case reads as a headline.
Should I A/B test subject lines in cold email?
Yes, but judge by reply rate, not open rate. Open tracking is unreliable and opens without replies are worth nothing.