Step 1
Enter your subject line
Type or paste your email subject line into the input field. The tool analyzes it in real-time as you type, showing character and word counts instantly.
Email Subject Line Tester
An email subject line tester analyzes your subject line across eight key dimensions - length, word choice, spam triggers, emoji usage, personalization, urgency, question usage, and numbers - and provides an overall score with actionable suggestions to improve open rates.
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How to test your email subject line
Step 2
Review your scores
The tool scores your subject line on eight dimensions: length, word choice, spam triggers, emoji usage, personalization, urgency, questions, and numbers. Each dimension is rated with specific feedback.
Step 3
Apply the suggestions
Read the actionable improvement tips and revise your subject line. Test multiple variations to find the highest-scoring option before sending your campaign.
Frequently asked questions
What makes a good email subject line?
A good subject line is 30-50 characters long, uses power words that create curiosity or urgency, avoids spam trigger phrases, and clearly communicates the value of opening the email. Personalization tokens like the recipient's name can boost open rates by 20-26%.
How long should an email subject line be?
The optimal length is 30-50 characters (6-10 words). Subject lines under 30 characters may lack context, while those over 50 characters get truncated on mobile devices. Most email clients show 35-45 characters on mobile and up to 60 on desktop.
Do emojis help email open rates?
Emojis can increase open rates by up to 56% when used sparingly (1-2 per subject line). They help your email stand out in crowded inboxes. However, overusing emojis (3+) can trigger spam filters and reduce credibility, especially in B2B contexts.
What words trigger spam filters in subject lines?
Common spam triggers include 'buy now', 'free', '100%', 'act now', 'limited time offer', 'click here', and excessive punctuation (!!!, ???). Using ALL CAPS for entire words also increases spam likelihood. Modern spam filters evaluate the full email, but the subject line is weighted heavily.
Should I use questions in email subject lines?
Yes, questions can be very effective because they create a curiosity gap that compels recipients to open the email for the answer. Questions like 'Are you making this common mistake?' perform well. However, avoid yes/no questions that can be answered without opening.
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