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Subject Line Tester

This subject line tester scores an email subject from 0 to 100 in your browser. It checks the length, listed spam phrases, emoji, repeated exclamation marks and personalization tokens, and shows how the subject is cut off on mobile and desktop. The score is an editorial guide, not an open-rate forecast.

Subject Line Tester
Example result
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  • Processing Local example ready
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How to Use the Subject Line Tester

Run an email subject line test by entering the subject, reading the score and each check, and adjusting the wording until the previews read well.

  1. Type or paste the subject line you plan to send.
  2. Select Test subject to score it from 0 to 100.
  3. Read each check: characters, words, emoji, personalization tokens and spam wording.
  4. Compare the mobile and desktop previews, adjust the wording and test again.

What the Email Subject Line Tester Checks

The email subject line tester checks length, spam wording, emoji, punctuation and merge tags, the issues you can fix before a subject is sent.

Email Subject Line Character Limit

Subjects between 15 and 60 characters pass the length check; shorter or longer ones lose 20 points. The mobile preview cuts the text after 35 characters and the desktop preview after 70, so put the useful words first. Real cut-off points depend on the screen, the font and the email app.

Spam Subject Line Checker

The tester looks for a short editorial list of phrases often associated with spam, such as act now, risk free and click here. Each match costs 10 points, up to 40, and more than one exclamation mark costs another 10. Mailbox providers use their own filters, so a clean result does not guarantee the inbox.

Emoji in Email Subject Lines

Emoji are counted, and more than two in one subject lowers the score by 10 points. One well-chosen emoji can help a subject stand out, but some apps show it as an empty box and it adds noise to business mail. Personalization tokens like {{first_name}} or *|FNAME|* are listed so you can confirm your sending platform will fill them.

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Frequently Asked Questions

How Long Should an Email Subject Line Be?

Aim for about 30 to 50 characters and keep the key information in the first 35, which is roughly what a phone shows. This tester flags anything under 15 or over 60 characters, but a clear longer subject is better than a vague short one.

What Is a Good Email Subject Line?

A good subject tells the reader what the email is about and why it matters to them, without tricks. It is specific, honest about the content and free of spam phrases and excessive punctuation.

Should an Email Subject Line Be Capitalized?

Both sentence case and title case are acceptable, so choose one style and use it consistently. Avoid writing whole words in capital letters, which reads as shouting and is a common spam pattern. This tester does not score capitalization.

What Is Subject Line Testing?

Subject line testing means checking a subject before you send it, or sending two versions to small groups and keeping the one with more opens. This tool covers the first part; run A/B tests in your email platform with real recipients.

Related Email Tools

Email Subject Line Generator Write ten scored email subject lines for a topic, goal and tone from structured templates. Email Spam Checker Score email content against transparent local rules and see which wording deserves review. AI Email Writer Turn your key points into an email draft from templates for five common messages and three tones, with no AI model. HTML Email Preview Render pasted email HTML at phone, standard and desktop widths, and lint it for code that Gmail and Outlook drop. Plain Text to HTML Converter Convert a plain-text email to table-safe HTML with inline styles, or turn email HTML back into wrapped plain text.

Continue with the guide Why Are My Emails Going to Spam?. Investigate configuration, content and reputation.

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