Do your subject lines draw readers in and drive them to open your emails?
If not, you need to make use of an email subject line tester before hitting send.
But what's an email subject line tester?
It's a tool that analyzes email subject lines and tells you what you need to do to improve them. It checks for factors such as length, emotion, grammar, punctuation, personalization, etc.
Why should you care about subject lines?
Consider how many emails your recipients receive in a day from different sources. Then, factor in research reporting that the total number of emails sent and received is projected to reach 392.5 billion in 2026.
Image via Statista
This begs the question:
Why should the recipient choose to open your email over others?
It's for this reason you need a subject line tester.
You need a tool that can increase your chances of getting higher open and click-through rates for your emails. A tool that recommends what words you need to change or include to improve deliverability and readability.
But which are the best subject line tester tools?
Find out below.
Subject lines are the first thing your recipient sees in their email inbox.
These are often the deciding factor on whether the recipient opens your email or not. Therefore, it's crucial to stop relying on intuition and leverage tools that offer cold hard data on creating subject lines that work.
And in this section, we list out the best subject line tester tools your business can use to improve your email open rates.
Check these out.
Image via Zurb
This subject line tester ensures that your subject lines display properly in the recipients inboxes without cutting off words.
Since most people open emails based on subject lines, you need to ensure you write subject lines that increase click-through and open rates so that you can increase conversions.
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Pro Tip: Use Zurb to preview how your email subject lines will appear on mobile phones and optimize them where necessary.
Image via SubjectLine.com
This subject line tester gives you an overall score of your subject line with reasons that made you lose points.
It's one of the email marketing tools you can leverage to better understand what kind of email content can improve open and response rates.
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Pro Tip: Integrate SubjectLine.com with ChatGPT and use it to create catchy and more effective subject lines.
Image via CoSchedule
Improve your email and newsletter open rates by leveraging this subject line tester from CoSchedule.
Why use it?
You get suggestions on how to optimize the subject line for higher open rates.
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Pro Tip: Use personalized subject lines to create an instant connection with your audience.
Image via SendCheckIt
This subject line tester claims to compare your subject line against more than 100K other emails sent by marketers.
And considering how content personalization is crucial, this subject line tester also scores your performance based on this factor.
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Pro Tip: You can use SendCheckIt to optimize more than just your subject lines; use its generative AI to improve your entire email creative workflow by miles.
Image via Automizy
Unlike other subject line testers that score against best practices, Mizy leverages deep learning to analyze email campaigns and make predictions.
It's an artificial intelligence-powered email marketing tool that grades subject lines using data from over 1 million campaigns.
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Pro Tip: You can get in depth insights into what’s wrong with your email subject lines with Mizy. This will help you learn and adapt with time.
Image via Moosend
With the Refine subject line tester, you leverage artificial intelligence to test subject lines and create those that resonate with your audience.
And if you want to improve your email lead generation and conversion rate, you need to leverage a subject line tester like this one to get higher open rates.
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Pro Tip: You can use Refine by Moosend to analyze your subject lines based on the number of subscribers you have and the specific Industry you operate in.
Image via Advanced Marketing Institute
If you want to find the emotional marketing value of your subject lines, you can use this headline analyzer by AMI. It is technically not an email subject line tester but can act as one for this specific purpose.
And since successful copywriting requires you to write content that touches your clients emotionally, you need a subject line tester that factors in this variable.
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Pro Tip: Go one step further by using AMI’s copy analyzer to check for flaws in your email body and fix them.
Image via Capitalize My Title
This subject line tester uses over 60 different data points to score your subject lines.
Want to know the best part?
You can use it to capitalize your subject lines once you finish correcting them for readability and deliverability.
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Pro Tip: Use Capitalize My Title’s Email Subject Line Tester to search for power words that can help you create more attention-grabbing subject lines.
Image via EmailTooltester
The Free Subject Line Tester by EmailTooltester is a web-based tool that helps marketers optimize their email subject lines for better display.
You can have a real-time preview of how your suggested subject lines appear on various mobile devices in just a few seconds. This way, you can fine tune your subject line and email based on the preview to get more opens.
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Pro Tip: Preview variations of your subject line based on lengths, word choices, exclamation points, and other elements to see which one catches the eye most effectively.
Image Via IsItWP
With the IsItWP email subject line tester, you can ensure that your subject lines have the perfect word balance, are scannable, and get straight to the point.
Additionally, it can help you leverage power words that improve your open rates.
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Pro Tip: Use IsItWP’s Email Subject Line Analyzer to optimize the word count, character count, and emoji count of your subject lines.
Image via Mailchimp
If you are looking for a subject line tester that offers comprehensive features to ace your email marketing campaign, Mailchimp is a great choice. Its Subject Line Helper is a tool that comes free with your Mailchimp account.
In addition to offering a subject line tester tool, Mailchimp is used to build ad campaigns, create beautiful landing pages, and send branded emails.
Let’s see what else makes Mailchimp an effective subject line tester.
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Pro Tip: Use IsItWP’s Email Subject Line Analyzer to optimize the word count, character count, and emoji count of your subject lines.
Image via Postmark
Are a large amount of the emails you send being marked as spam?
You should consider using a subject line tester tool such as Postmark’s Spam Check. This tool not only acts as a subject line tester but also helps ensure that none of your emails are being misfiled as spam.
Read on to know what other features make the Spam Check a viable subject line tester tool.
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Pro Tip: You can use Spam Check by Postmark to check all components of your email, including subject lines, full headers, and content.
Image via Omnisend
Omnisend is a must-have subject line tester tool for teams who are serious about how they write emails. In addition to subject line testing, the tool also helps you with segment testing, email reporting, and email marketing automation.
You can A/B test your email subject lines to zero in on the best one.
That’s not all. The subject line tester evaluates words, characters, and the length of the subject line and gives you suggestions on replacing spam-triggering words with safer words.
Check out this subject line tester’s features, pros, and cons.
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Pro Tip: Use Omnisend’s A/B testing feature to compare different variations of email subject lines and pick the one that performs best.
Image via Mailmeteor
Mailmeteor is an intuitive subject line tester that uses advanced AI algorithms to score your subject lines based on several criteria. It considers features like email length, number of question marks, exclamation marks, emojis, spam words, and much more.
This tool works so well as one of the best email subject line testers because it doesn’t just analyze your subject lines, but you can also generate powerful subject line ideas to choose from.
Let’s take a closer look at its key features.
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Pro Tip: Looking for a potential lead’s email address? Use Mailmeteor’s email permutator to find it.
Image via Mailshake
Mailshake is a great tool for any marketer who needs to run an email campaign. It's an easy-to-use subject line tester that will help you send out emails that deliver the results you seek.
With Mailshake, you don’t need to worry about creating email campaigns. It offers a variety of features such as A/B testing, automation, and drip campaigns. You can also use Mailshake for social media marketing and website traffic optimization.
Check out the features of this subject line tester.
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Pro Tip: You can make your emails easier to read by using Mailshake’s Email Copy Analyzer to find words that are difficult to read and replace them with easier ones.
Q1. How do you test a subject line?
A. Use a subject line tester like the one offered by Attrock to test various aspects, including:
Q2. Why is subject line testing important?
A. Testing your subject lines before sending the emails helps you optimize them and ensure that they get the desired open rates. Subject line testing can help you avoid common mistakes and create engaging and high-converting subject lines that compel recipients to click on your email.
Q3. What is Subject line A/B testing?
A. It's a process of comparing how one version of your email subject line performs when sent to an audience compared to another.
For example, you can send one version of your subject line to a percentage of your recipients and send another version to the rest. Then, after comparison, the subject line that receives the most opens emerges as a winner.
You can then use this winning subject line when sending emails to the rest of your contacts.
Q4. What is the most reliable way to test whether your subject line will get more people to open their email?
A. The simple answer is to use a subject line tester to optimize your subject lines before sending your emails. These tools analyze your subject lines on multiple parameters and give suggestions on how to improve them.
Q5. What is subject line optimization?
A. It is the process of analyzing your subject lines using a testing tool and then incorporating the suggestions provided to make them more engaging.
Q6. What are subject lines?
A. Subject lines are a sort of introduction to an email and are visible in a recipient’s inbox even if they do not open an email. Email subject lines provide information about the email and help people decide whether they want to open the email.
Q7. Are subject line testing sites valid?
A. Yes, they are.
They make the process of testing subject lines easier and provide a detailed analysis of subject lines and ways to improve them.
Q8. Which is the best email subject line tester?
A. Use this list to find some of the best email subject line testers:
With the right subject line tester, you can improve deliverability and open rates of your emails.
So, keep testing your subject lines, analyze different metrics, and see what works best for your recipients.
Which of the subject line tester tools do you like?
Share your experience with the subject line tester and how it helped you improve your email marketing results in the comments.
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