Subject lines are the first gate. Bad subject line, zero opens. Good subject line, 40-60% open rates. In B2B cold, the rules are specific and nearly opposite to consumer email marketing.
"your post on retention"
"saw your Q3 announcement"
"re: your hiring push"
"quick thought on pipeline"
"thoughts on [specific topic]"
"[Mutual name] said to reach out"
"from [company] to [their company]"
"odd question about [department]"
"something you might've missed"
"15 min next week?"
"introduction from [referrer]"
Generate 15 cold email subject lines for: - Target: [role + industry] - Email topic: [what the email is about] - Context trigger (if any): [recent event] Rules: - 3-5 words max - Lowercase - No emojis, no symbols - Should feel like a peer wrote them, not a marketer - Mix: specific observation, curiosity, direct, name-drop Just the subject lines, numbered.
A/B test 2 subject lines per campaign at minimum. Split 50/50 for the first 200 sends. Keep the winner, test a new challenger against it. See what to test.
Typical open rates by subject line quality:
With iOS 15+ inflating open rates through prefetching, treat opens as directional not absolute. Reply rate is the truer signal.
Related: headlines in direct response, the same principles scale from email subjects to landing pages.