Email Glossary
Subject Line
The subject line is the first thing recipients see in their inbox and is the primary factor in open rate optimization. Good subject lines are clear, relevant, and accurately represent the email content. Misleading subjects hurt deliverability and increase unsubscribe rates.
Subject Line Best Practices
Keep subject lines under 50 characters for mobile display. Use personalization like the recipient name when available. Avoid ALL CAPS, excessive punctuation, and spam trigger words. Test different subject lines through A/B testing to find what works for your audience.
Related Terms
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