What makes a good email subject line?
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A good email subject line is 30-50 characters long, creates curiosity or urgency, is specific and clear, avoids spam trigger words, includes personalization when possible, and accurately represents the email content. Subject lines that are concise, compelling, and relevant typically achieve 30-50% higher open rates.
What is the ideal subject line length?
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The ideal email subject line length is 30-50 characters. Subject lines in this range perform best across all email clients. Mobile devices typically cut off subject lines at 35-40 characters, so keeping it short ensures your message displays fully. Subject lines under 30 characters often lack context, while those over 50 characters get truncated.
What words should I avoid in subject lines?
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Avoid spam trigger words like FREE, URGENT, ACT NOW, LIMITED TIME, WINNER, CONGRATULATIONS, CLICK HERE, BUY NOW, and excessive punctuation (!!!, $$$). Also avoid ALL CAPS, deceptive claims, and overly promotional language. These words trigger spam filters and decrease deliverability. Instead, use specific, honest language that creates genuine interest.
Do emojis help email subject lines?
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Yes, emojis can increase open rates by 5-10% when used appropriately. They grab attention in crowded inboxes and convey emotion quickly. However, use them sparingly (1-2 maximum), ensure they're relevant to your content, test across email clients for compatibility, and consider your audience—B2B audiences may respond differently than B2C.
How are email subject lines scored?
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Email subject lines are scored based on multiple factors: length (30-50 characters is optimal), spam trigger words (presence decreases score), capitalization (too many caps hurts), personalization tokens (increases score), questions (drive curiosity), numbers (grab attention), and emojis (when used appropriately). Our tool analyzes all these factors to give you a score out of 100.
Does personalization improve open rates?
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Yes, personalized subject lines improve open rates by an average of 26%. Including the recipient's name, company, location, or other relevant personal details makes the email feel more relevant and less generic. Use merge tags like {{FirstName}} or {{Company}} to dynamically insert personalized content. However, ensure accuracy—wrong personalization hurts more than generic subject lines.
Should I use questions in subject lines?
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Questions in subject lines can be highly effective, increasing open rates by 10-15% when done well. They create curiosity and engagement. The key is asking questions that are relevant to your audience's pain points or interests. Avoid yes/no questions; instead, ask questions that create a knowledge gap the reader wants to fill by opening the email.
How often should I test subject lines?
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Test subject lines for every important email campaign. A/B test at least 2-3 variations per campaign, sending to a small segment (10-15% of your list) first, then sending the winner to the remainder. Test one variable at a time (length, personalization, emoji, urgency) to understand what drives results. Regular testing helps you understand your specific audience's preferences over time.
