A good cold email subject line is short, specific to the lead, and low key. Keep it under 45 characters so it is not cut off on mobile. Hint at something relevant to them and avoid hype. If the subject does not get opened, nothing else in the email matters.
Here is how to write subject lines that earn the open, and bodies that earn the reply.
What good subject lines share
- Short: under about 45 characters so it fits on mobile.
- Specific: hint at something about them, not a generic pitch.
- Low key: sound like a person, not a campaign. No all caps, no triple exclamation marks.
- Curious, not clickbait: make them want to open without over promising.
Formulas that work
- Company plus a question: "Glow Med Spa, quick question"
- Observation: "noticed you opened a second location"
- Common ground: "fellow clinic operator"
- Benefit hint: "faster follow-up for new inquiries?"
The body matters too
Keep it short. Open with something specific to them, give one clear reason you are reaching out, and end with one easy ask. Assume they never saw your LinkedIn message, so the email should stand alone.
Personalize at scale with AI
On the HeyReplyAI Pro plan, the AI writes a subject and body for every lead, exported as {email_subject} and {email_body}. Pair it with your LinkedIn sequence for true multichannel outreach.
Write your whole HeyReach sequence with AI
HeyReplyAI writes a personal connection note, every follow-up, and an optional cold email for each lead. Then it sends them into HeyReach as custom variables. Start free with 25 leads.
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