Reply Rate
The percentage of delivered emails that received a reply from the recipient.
Reply rate is the most important metric in cold email because replies indicate genuine interest. A good reply rate for cold email is 3-8%, though this varies widely by industry and offer.
Positive replies (interested prospects) are what you're optimizing for, but even negative replies ('not interested') are better than no response — they show your emails are being read.
To improve reply rate: personalize beyond first name, lead with value, ask a clear question, keep emails short (50-125 words), and follow up consistently (3-5 touches).