This plugin hasn’t been tested with the latest 3 major releases of WordPress. It may no longer be maintained or supported and may have compatibility issues when used with more recent versions of WordPress.

Subject Line Scorer


The only subject line tester plugin for WordPress.

Display a performance score next to email subject lines in your blog posts, using a simple shortcode.

Show off your subject line writing skills. Educate your readers by revealing the process of how you come up with subject lines that get higher open rates.

At the heart of this plugin, there’s an AI engine that has been trained on data from over 100K campaigns. Even the most seasoned email marketer doesn’t have that kind of experience. Also, Mizy continuously learns from new data, so the results you get are always up to date.

Step 1: Select the subject line you’d like to get a score for.
Step 2: Click on the „Score Subject Line“ button.
Step 3: A pop-up appears where you’ll see your score, click on „INSERT SCORE“ and you’re done.

Note: You can select more subject lines at once. In the pop up you can delete the subject lines you don’t want to display.



  1. Install Subject Line Scorer from WordPress Directory
  2. Activate the plugin through the ‘Plugins’ screen in WordPress
  3. Now you are free to use it in your Classic Editor 🙂


What does the score mean?

It provides an interpretation for the strength of your subject line.
Mizy applies two types of scoring:
* Quantitative value: A higher score means your emails are more likely to be opened. Note: subject line is only one – but the most significant one- of the three factors (sender name, sending time, subject line) that determine the open rate of an email.
* Color of the badge: It provides a visual interpretation of the strength of your subject line. There are three colors: red, yellow, and green. Based on the results of 100k email campaigns, your subject line would perform – according to the color- poorly, fairly or remarkably. We recommend you to always aim for green and never go below yellow.

Is it truly Artificial intelligence?

Of course, it is! If you want to get a sneak peek of what lies under the hood, check out this article. Also, our AI research team sends you their best wishes.

Is it free?

Yes, it is.

Can I score other than email subject lines, e.g. headlines, taglines?

Not right now. Mizy is still learning. However, naturally, there will be other use cases: it will score and optimize ads, headlines, and call to action buttons for you.

Is it compatible with Gutenberg?

Currently it is compatible only with the Classic Editor, however soon we plan to release Beta version for Gutenberg.


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Contributors & Developers

“Subject Line Scorer” is open source software. The following people have contributed to this plugin.


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Interested in development?

Browse the code, check out the SVN repository, or subscribe to the development log by RSS.