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Crafting the perfect newsletter requires a lot of effort. You spend a lot of time over an ideal email copy, embedding the correct links, designing it properly, and strategically placing your call-to-action to nudge your subscribers to take action.

But it can all go down the drain if the email is not even opened. Research shows 33% of email recipients decide to open an email based on its subject line. Another 69% of respondents confessed they would report an email as spam after solely reading the subject line.

It is, therefore, essential to include well-thought subject lines in all your emails. A great example of catchy subject lines is newsletters from Glitter Guide. The company sends lifestyle-related newsletters to its subscribers.

Considering there is a new trend to talk about every day, Glitter Guide identifies a need for freshness in all content related to it. So, it connects the newsletter headlines with the latest news to ensure its readers find the newsletter relatable and click-worthy.

Similarly, you must study your audience well and test what works for them. But a universal fact is that most inboxes where your newsletter lands are already overflowing with emails. So, you must ensure your headline stands out among them.

A great subject line comprises numbers or data, a unique rationale, attention-seeking information, and a promise. To create a catchy headline for your newsletter, you must balance creativity with customer knowledge to get optimum results.

If all this sounds like too much work, technology has got you covered. Email subject line testers are tools that come with various features and use advanced tech to help you quickly write the best headlines. These tools consider multiple aspects of a headline that impact your audience.

They measure the usage of emotional words, keep words that trigger spam filters at bay, and suggest the perfect headline length. GeekFlare explores eight incredible tools:


The Omnisend tool gives you a data-backed score (percentage) of your newsletter headline. The tool evaluates your copy to generate a score and recommends improvements in it. Shown below is an analysis of the subject line, “Recipe blog update: revenue up 45% from last year.”

Omnisend headline analyzer displays length along with the breakup for the number of words and characters. It gives you suggestions to replace spam-triggering terms with safer words. Plus, it checks the capitalization style and use of numbers.

You can also check a preview of your newsletter subject line on desktop and mobile devices, making it a relatively comprehensive tool to use, just like Omnisend.


This is a content marketing software solution, but it is also known in the market for offering an email subject line tester. The tool is mainly focused on creating subject lines that are relatable and convert more.

CoSchedule rates your subject line based on words that increase the open rates of your email. It specifically promotes the usage of positive words which can be easily picked from its exclusive Word Bank. CoSchedule email headline analyzer suggests removing negative terms.

The tool even gives you feedback on the case that works best for newsletter subject lines. Besides, you can get other relevant details such as character count, word count, and emoji counts.

CoSchedule email subject line analyzer also offers an appearance preview to help you see how the subject line will look on desktop and mobile. Is it not amazing?

Send Check It

Send Check It offers an in-depth email subject tester tool. It compares the headline of your newsletter against more than 100,000 marketing emails. The scores generated by the tool are based on this comparison. It gives you a result that has been proven to work.

Besides the score, it gives you a recommendation on how to improve your subject line. It rates your subject line on 16 parameters. Send Check It checks the headline for length and readability. The tool also offers a preview of the email in the inbox of your target audience.

It includes how the email headline and sender name might appear on mobile and desktop views. You can also perform an in-depth sentiment analysis of your newsletter subject line.

The tool helps you determine the emotion (positive, negative, or neutral) your subject line will evoke in your readers. The tool performs a complete check, including scanning words that spam filters might flag.

For instance, it runs a check for a fake “RE:” or “FWD:” at the beginning of your subject that could temporarily boost your open rates.

In addition to reading grade level, the tool reviews the proper use of punctuation, capitalization, and emojis. Among other things, the tool also helps you personalize the content of your newsletter to boost open rates.


Automizy launched Mizy to make content creation easier. Mizy is an AI-powered bot that helps you find the perfect email subject line for your newsletter. The tool is designed to rank headlines by comparing them against existing campaigns.

It compares the performance of these campaigns and suggests click-worthy subject lines to improve the open rates of your newsletter. Mizy uses Deep Learning to help you write better headlines for your newsletter.

It accesses a database of emails to analyze the open and click-through rates. The insights make AI-driven Mizy classify campaigns into those performing and others that are underperforming.

The bot generates a performance-based rating of your headline and rates it out of 100. It also provides tips to improve your copy. The only thing is Mizy is still in the Beta phase, and there might be bugs and issues you encounter while using the bot.

Nonetheless, it is an interesting email tester with a lot of potential, which provides subject lines as if you wrote them.


Design and branding solutions provider Zurb offers a tool known as Test Subject to review headline appearance on mobile devices. Most people access emails over their mobile devices, and their number is bound to increase with the exponential rise in digital adoption.

Zurb realized the email subjects and preview are truncated on these devices. A poor display of headlines may put off your reader. Incomplete sentences and inappropriate phrases may push all your efforts down the drain.

Test Subject is a tool to help you address these issues. It ensures your email headlines are compatible with all the latest smartphone displays in the market. The tool is easy to use and helps you create mobile-friendly headlines for your newsletter.

Test Subject offers a preview of the headline, sender name, and preheader text. This preview helps you ensure the subject line of your newsletter appears properly in your reader’s inbox.


Mailshake is the easiest-to-use headline analysis platform. Its free tool analyzes your copy for readability and spammy words. The email analyzer evaluates your email for length, words that trigger spam filters, and links. By “copy,” we do not just mean the subject line but also the email body.

It gives you specific recommendations to tweak your copy until deliverability and readability are improved. Mailshake recommends writing personalized subject lines with 30 or fewer characters to achieve an above-average open rate.

It even suggests creating a sense of urgency through the email headline but advise against using click-baits. According to its evaluation, if the email copy does not blend with your headline, it reduces the impact of your headline as well.

Mailshake is the ultimate tool to write compelling headlines with quick guidance and is a favorite amongst entrepreneurs, marketers, and salespeople to send custom cold emails in bulk.


This free tool is the simplest subject line tester that offers a top-level review of your email headline. It is helpful to analyze any subject line on marketing and performance parameters but do not expect your subject lines to be dissected in the case of other testers. analyzes your subject line for filtering and deliverability issues. You get an overall evaluation for your subject line after the tool runs it through a robust screening process. Your headline is analyzed against 800 unique rules and scored for them.

It allows you to see where and how to make the email headline better. The assessment is based on the performance of email messages sent and tracked by over time.

Is Not Spam

This tool helps you avoid trigger words in your email headline. It keeps your emails from getting flagged by spam filters. The free tool offers a comprehensive spam report by running your copy through five tests.

The tests include SPF Check, Sender-ID Check, DomainKeys Check, DKIM Check, and SpamAssassin Check. It captures words or phrases in your email subject line and body that are considered spam.

Is Not Spam identifies spam-related issues and suggests how to fix them in its detailed report. Besides, the email headline analyzer tool also reviews your email copy to ensure it is free of spam.

Ready to work on your email subject lines?

The above-mentioned tools will help you create the right headlines for your newsletter and improve your CTR. Some of them even offer deep insight to help you compare your newsletter against other campaigns that are running successfully.

However, it is advisable to test what works for your audience. You can pick a combination of tools that can help you boost your email open rates.

But more importantly, you must invest in writing well-written headlines as they capture the attention of your subscribers, improving the click-through rate (CTR) of your email.

They help you get the desired results from your newsletters, such as increased website traffic, landing page views, or enrolments.

Tips to remember to write converting email headlines

So, as you have realized the importance of a perfect email subject line and how it is essential to get a higher open rate, let us take a look at how you can create one quickly:

#1. Include an actual person’s name in the subject line

It instantly makes the email content more personal. You do not want your subscribers to think they are receiving emails from a bot. There is a human being sending out those newsletters, after all. So make sure you keep that informal connection steady by using the person’s name in the headline — similar to what Licious did in an email to me—a subscriber.

#2. Use power words

Absolutely! Words like “inspire,” “only for you,” and “faster” are powerful as they instantly grab the attention of the email recipient and create a sense of urgency for them. Of course, the use of power words depends on the context of your email. So if you think you can do away with them, keep your email headings short and simple. Otherwise, you can also use high-conversion words as shown below:

#3. Test your subject lines before sending

Use any of the above tools we mentioned previously to optimize your email subject lines for conversion. You might get some right and also write poor email headings at times. These testers will ensure that only quality subject lines are used in your newsletters.

#4. A/B test your subject lines while sending

You could come up with a thousand email headings, but to ensure your subscribers like them enough to open your email, you must A/B test them. Email service providers like ActiveCampaign, SendGrid, and MailChimp can guide you through the split testing process.

#5. Do not forget about emojis

Research shows 92% of online consumers use emojis every day. With over 10 billion emojis sent daily, this is not surprising at all. So why not use them in moderation in your email subject lines? Copy-paste relevant emojis from sites like and use them in your content.

Of course, do not go overboard with the number of emojis used. Treat them as garnish and only add them when it makes sense or when they support your message. The idea is to get noticed, not send mixed signals to your email recipients.

Over to you

Regardless of your industry, writing quality email subject lines is essential. Thankfully, there are tools to help you sort out and improve your open rates significantly. Your email subject lines have the potential to increase user engagement and shareability rates — bank on them, work hard on them.

Good luck!

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  • Asavari Sharma
    Asavari is a B2B content strategist and web journalist. She is known for her strategic and authentic marketing initiatives that help SMBs across the globe drive sales and make profits. She is also an advocate of a healthy work-life balance.

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