Cold Email Subject Lines That Actually Work in 2026: 50 Examples
Frequently Asked Questions
Find answers to common questions about email verification.
How long should a cold email subject line be?
Under 50 characters. The optimal range is 6 to 10 words (Marketo/Boomerang, 2024). Forty-five percent of emails are opened on mobile, where longer subject lines truncate.
Should you personalise a cold email subject line?
Yes. Personalised subject lines see 22% higher open rates than generic ones (Experian, 2024). But the personalisation must be real. A merge field with a template body is worse than no personalisation at all.
What words should you avoid in a cold email subject line?
Avoid spam trigger words: free, guarantee, urgent, limited time, no obligation, click here, winner, earn, cash, save, lowest price, risk-free, congratulations. Combinations of two or more are worse than any single word. These reduce deliverability at the filter level.
How do you A/B test cold email subject lines?
Change only the subject line. Keep body, list, send time, and sender name identical. Send each variant to at least 100 contacts. Test formula against formula (F1 vs F2) before wording variations. A meaningful result is a 5-percentage-point difference on 200 or more contacts.
What is the best cold email subject line?
There is no single best subject line. The best one for a specific prospect references something real about their company, role, or recent activity. The 8 formulas in this post give you a repeatable system for any prospect. For full examples, see our personalized cold email examples.
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