Email Subject Line Tester

Test the performances of your email's subject and generate AI-powered alternatives.


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Your subject line

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Alternatives suggested by AI

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Alternatives from GPT-3

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The fastest tester and generator of email subject lines

Email Subject Line Tester by Mailmeteor scores your email subject line instantly for free. It's also a generator of subject lines thanks to AI, to provide alternatives and help you select the best one.

Tests are made at multiple levels: length, number of words, number of question mark and exclamation points, presence of emojis or spam words. Make sure your emails reasonate with your audience.

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How it works

Learn why and how to test your email subject lines with our 2-min video tutorial.

Trusted by 5 million professionals

Questions & answers about email subject line tester

Everything you need to know about how and why checking email subject lines.

Email subject line tester is a free, easy to use and simple tool. Enter the email subject line to generate alternative subject lines and score all of them so you can you choose the best option for your campaigns.

Email subject line tester is a free tool to test anyone’s email subject line. It tests that the email subject line is well conceived, with the good length and without too much spam related wording. In case we detect something wrong, the email subject line score will decrease.

Email subject line tester proceeds with several checks to determine if an email subject line is valid:

  1. The email subject must be well formed, not too short and not too long.
  2. It should be grammatically correct, with first letter as a cap and ponctuation.
  3. The email subject can include emoji but they should not be too numerous.
  4. The subject line should not contain spam words.

Depending on the provided email subject line, we might apply extra-checks on a per basis.

An email subject line generator is a free tool to generate alternatives to a provided email subject line. It uses synonyms or rephrase the subject line, thanks to AI, to convey the same idea but in a more appealing tone. Increasing open rate and engagement with emails.

Your subject line is submitted to an AI (OpenAI GPT-3) that will suggest improvements. AI is not perfect (yet) and might suggest inacurrate responses. Please let us know of any inappropriate suggestions.

Email Subject Line Tester is totally free to use. Mailmeteor makes it available to anyone interested in checking an email subject line and make sure you will be read.

We apply a fair-use policy, so you are free to manually use Email Subject Line Tester as long as you don’t abuse of it. Any abuse includes, but is not limited to, making automatic requests to our service.

Your data stays yours - like all products made by Mailmeteor. Email addresses that you verify using our email subject line tester are not saved by us nor shared with a third-party. Although, we might temporarly log requests made to the service for maintenance purposes.

With this said, this page has Google Analytics and is protected by reCAPTCHA. Consequently, Google’s Privacy Policy and Terms of Service apply.

Once you have verified your email subject line and found the most efficient, you can send a highly personalized email campaign using Gmail with Mailmeteor. Mailmeteor lets you send mass emails in Gmail that feel personal. It’s the most popular Gmail mail merge tool, trusted by 5 million people worldwide for its simplicity and privacy focus.

Questions? Comments?

Feel free to let us know what you think.

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