Subject line tester tools have allowed the art of emailing to become a science.

Intrigued? Well, you should be. Through the years, the field of sales and marketing has increasingly embraced tech. This has largely been brought about by the need to connect better with prospects.

In the real world, nothing shows effort like first impressions. When it comes to email, subject lines are your first line of defense.

They either make you or break you.

Given the fact that 43% of email recipients only check out the subject line before categorizing it as spam or not, it’s important to read carefully. By all means, you should avoid the curse of the dreaded s-word.

How do you do so? Personalization.

That’s where it all starts.

You can boost your email open rate by as much as 2.6% by simply incorporating the recipient’s name in the subject line.

That said, there’s plenty more that you can do to enhance your numbers. In our review today, we’ll run through a couple of subject line tester tools to boost your clickability and deliverability.

This is an effective tactic if you’re looking to receive more replies from prospects. Read on!

Top 11 Email Subject Line Tester Tools

1. Test Subject

Test Subject is an incredible subject line tester tool. Right before you click send, you can preview just how the mail will appear on various mobile phone devices. The tool allows you to see a preview of the pre-header text, the manner in which the sender name is displayed and the subject line order.

Since some devices may truncate sender names and subject lines, it’s best to look for the most appropriate words. That way, you’ll avoid disastrous subject lines that are confusing.

Test Subject, Email Subject Line Tester

The more your test, the more likely you are to achieve peace of mind as you send out emails en masse. This is an incredibly helpful subject line tester tool if you’re looking to provide the same seamless experience to your prospects.

Price: Free

What it Tests: How your email is displayed on your prospects phones

How to Test: To get started, you simply need to copy and paste your text into the tool and you’ll get instant previews

2. Subject Line

Regarded by many as a quintessential tool among marketers, Subject Line is totally worth the hype. The tool is able to carefully evaluate subject lines according to tried and tested email marketing best practices and give instantaneous scores.

While the score range scale is 0-100, Subject Line shines since the results are more than just your run of the mill core. This is because you’re able to get context on why your subject line is rated as it is.

A good example of this is when your subject line falls below the threshold in enticing users. Impressively, Subject Line is able to deduce the reason behind this may be the lack of urgency in the content.

By providing immediate results, the tool allows you to play around with the subject line until you get it just right.

Price: Free

What the tool does: A comprehensive review of the subject line

How to Test: Fill in your details and the form and you’ll get instant feedback of the results

3. Email Subject Line Grader

Email Subject Line Grader is liked by many because of its simple intuitive user interface. It’s also robust enough to analyze different subject lines based on several aspects to determine just how alluring it is to prospects.

Email Subject Line Grader

To get started, you simply need to enter a single line in the tab and it will immediately give you feedback. You’ll be able to learn its opinion together with a rough assessment of your subject line. The assessment is based on the use of power words, word count, character count, and word mixture & balance.

Price: Free

What the tool does: Provides you with a score after evaluating your subject line

How to test: Key in your subject line in the open tab

4. Email Subject Line Tester

This is an excellent tool which allows you to check whether your subject line has spammy words. Email Subject Line Tester is able to do this by checking various parameters like personalization, reading level, and sentiment.

The all-inclusive sentiment analysis provided also scans crucial elements like and emoji use. After it’s done reviewing these parameters, it grades your subject line out of a 100.

From that, you can opt to proceed with the same subject line or change it altogether.

Price: Free

What the tool does: Checks the subject line for spammy words and provides an in-depth analysis of content

How to Test: Input the subject line in the tab and click on “Test Subject Now”

5. IsnotSPAM

This subject line tester tool provides users with a detailed spam report. IsnotSPAM works so well because it’s able to flag certain words and phrases in the subject line and email body. By making you aware of such words, IsnotSPAM allows your subject lines to not get tripped by spam filters.

In addition to this, the tool goes the extra mile by confirming whether your ID is clean and proceeds to suggest fixes for spam-related issues noted.

Other spam tests covered include SPF check and SpamAssassin check.

IsnotSPAM subject line tester

Price: Free

What it tests: Checks sender-ID and spammy phrase

How to Test: simply send an email to the provided email address on their homepage and you’ll receive a detailed spam report in a few.

6. HemingwayApp

Ernest Hemingway was renown for his direct writing style. As a marketer, directness is crucially important if you’re looking to appeal to prospects. As such, the Hemingway app was built to cater to writers who would like to simplify their copy.

The HemingwayApp effectively does this by carefully analyzing whether a layman can comprehend what you’re talking about. It’s very helpful if you’re looking to edit the body of your email. To get results, simply copy and paste the contents of your email into the tool and you’ll automatically get a readability grade.

From the results, you’ll learn how often you’ve used passive voice, number of adverbs and the hardest sentences to read.


You can put this tool to great use too when crafting your subject line. The beauty of it all is that it instantaneously shows results.

Price: Free

What it Tests: Readability of copy

How to Test: Copy and paste your content into the tab

7. Emotional Marketing Value Headline Analyzer

This is the perfect tool if you’re looking to determine how your subject line ranks when it comes to offering emotional marketing value. As alluded earlier, personalization is a great way to appeal to your prospects in an emotional way.

Once your copy is able to reflect this, you’ll be able to reach various audiences with ease.

Headline Analyzer masterfully analyses your subject line and provides a score based on the number of EMV words found. Other than this score, the tool also provides you with insights on the emotional aspects of your copy.

The emotional grading can either be spiritual, empathetic, or intellectual. This means you’ll be better informed when choosing which empathetic, spiritual or intellectual side of your prospects you’re targeting.

Emotional Marketing Value Headline Analyzer

Price: Free

What it Tests: the emotional value of your subject lines

How to Test: fill in the tab and you’ll get results on how your copy fairs on the EMV scale

8. CoSchedule’s Email Subject Line Tester

CoSchedule’s Email Subject Line Tester is just one of those must-have tools when evaluating subject lines. Admittedly, the tool was initially conceptualized to provide guidance when formulating headlines for blogs and articles.

Still, it impresses when used to craft email subject line.

It is able to do this by providing users with an all-inclusive assessment together with some actionable tips. The guide will help you improve the subject line in terms of grammar, structure, and word placement.

Given these qualities, it’s the ideal tool for marketers looking to perfect their subject lines.

8. CoSchedule’s Email Subject Line Tester

Price: Free

What it Tests: analyses subject lines

How to Test: key in your subject line, fill out the sign-up form, and you’ll access the results

9. Touchstone

As a premium marketing tool, Touchstone works best if you’re in a group setting. Depending on your rank, you’ll have access to email reporting functionality, filter options, tech support, subject line testing option and segment testing.

Touchstone Email Subject Line Tester

Once you get feedback on the aforementioned topics, you can easily compare your results with the rest of the 21 billion emails that are contained in Touchstone’s database.

The results are instantly provided and accurate. According to their proprietary algorithm, they are able to predict how subject lines fair to within 1-2% of actual open rates. An impressive stat.

You can create a virtual simulation of your email marketing database and oversee the open, click and delivery rates.

At the dashboard, you also have the flexibility to optimize every step of the email marketing journey. This means that the tool is robust enough to allow you to enhance performance as your subscriber base grows.

Price: 7 days Free Trial, Essential $69, Expert $99, Enterprise $297

What it Tests: The effectiveness of your subject line by giving comprehensive dashboard reports and providing access to Touchstone’s impressive database

How to Test: Sign up on their platform, test your subject line and compare results on their database.

10. PutsMail

Many people usually craft a subject line and press send without really caring as to how the email will look once delivered to readers. This is not the best approach if you’re looking to really resonate with audiences worldwide.

Thankfully, PutsMail has a solid system that helps you envision how the email, down to the subject line, appears. They provide a complete HTML and Apple Watch mock-up of how the message appears.

This is a really important strategy since it immerses you in the prospect’s world. With this view, you’ll be able to accurately tell exactly how they see your email once they open it.


In essence, PutsMail helps you avoid lengthy subject lines. While at it, you can ensure that the coding used is impressive enough. The tool excels by detecting potential issues and allowing you to make edits.

Price: Free

What it Tests: Allows you to see how your email appears to prospects before you send it out.

How to Test: Key in up to 10 email recipients, add a subject line, the body and choose the mock-up version either HTML or Apple Watch that you’d love to see in action.

11. Email Spam Tester

This tool has a couple of paid features that allows you to share results with a team. Since you can monitor the results in real time, it’s incredibly helpful when evaluating weak spots.

Their delivery duration tracking feature is brilliant since it lets you know whenever issues like ISP throttling arise. This means that you can prepare in advance before issuing out time-sensitive promotions and essential transaction emails.

With authentication testing as part of their M.O., you can check sender authentication every time. This allows you to know whether your message passes through SPF and DKIM authentication.

Email Spam Tester also thoroughly grades various elements in your email drafts and provides guidance on how you can improve your copy.

Email Spam Tester

Price: From $39 a month

What it Tests: detects spammy content and provide suggestions on how to improve deliverability, ROI and email open rates

How to Test: you have to send a copy of your email to the address provided on their homepage and await the report generated.


It’s important to have subject lines that mean something. After all, they play a big part in many email campaigns.

By making small tweaks to the phrases you use, you can realize plenty of benefits. As you get into your creative space, it’s always great to picture what prospects would like to hear from you. That way, you’ll be able to craft scintillating subject lines that prompts them to open.

If you’re unsure how to get started with this, we’re certain the tools listed above will do just the trick. Feel free to share in the comments your take on the best tester tools.


Kevin Thomas Tully is a globally-recognized Social Selling and Big Data strategist who employed the principles of Social Selling long before the term entered the popular business vernacular. A Johns Hopkins-trained data scientist, Kevin has applied true buyer intent data, predictive analytics, and data mining to the sales and marketing process for more than a decade to gain a strategic marketplace advantage for leading brands worldwide.

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