Your subject line is the gatekeeper to your cold email. It doesn't matter how brilliant your email body is if nobody opens it. We analyzed over 100,000 cold emails across our client campaigns to find the subject lines that consistently achieve 60%+ open rates.
Here are the 47 best performers, organized by category, with the psychology behind why they work.
Important Note
These subject lines work because they're relevant to the recipient. A great subject line sent to the wrong audience will still fail. Always ensure your targeting is on point before worrying about subject lines.
Personalized Subject Lines
Personalization is still king. These subject lines use the recipient's name, company, or specific details to stand out.
Curiosity-Driven Subject Lines
These create an open loop that the recipient wants to close by opening the email.
Value-First Subject Lines
Lead with what's in it for them, not what you're selling.
Referral/Connection Subject Lines
Social proof and mutual connections dramatically increase open rates.
Follow-Up Subject Lines
Most responses come from follow-ups. These subject lines keep the conversation going.
What Makes These Work
Analyzing the data, successful subject lines share these characteristics:
- Short: 3-6 words perform best. Mobile truncation starts around 30 characters
- Lowercase: All lowercase feels more personal, less promotional
- No spam triggers: Avoid "free," "urgent," excessive punctuation
- Specific: Mention their company, industry, or situation
- Natural: Sounds like something a human would write to a colleague
Subject Lines to Avoid
These patterns consistently underperform:
- ALL CAPS or Title Case Every Word
- "I wanted to..." (weak, seller-focused)
- "Introduction from {Company}" (sounds like a newsletter)
- Questions that are obviously rhetorical
- Clickbait that doesn't match the email content
Want Subject Lines That Convert?
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