13 of the Best Email Testing Tools to Improve Your Campaigns

There’s a lot that happens after hitting send — and a lot that can go wrong. Some errors are more of an inconvenience like a headline that gets truncated, while other issues can mean that your well-intentioned emails end up in the dreaded spam folder. 

Whether it’s crafting a newsletter or composing transactional emails, many resources, let alone time, get invested in the process. Sure, email analytics can help you to identify potential issues and make improvements, but that’s only after you’ve sent the actual email. What if you could make some of those changes that would improve your campaign performance before sending out the first rounds of emails? 

Enter email testing tools. From testing subject lines to preview testing to spam tests, there’s a long list of email testing software solutions and platforms aimed at brands, developers, and marketers, and many of them are free. To help you unlock the ROI potential of this effective marketing channel, here are 13 of our top picks in no particular order.

13 of the Best Email Testing Tools to Improve Your Campaigns:

13 Top Email Testing Solutions

1. Omnisend


Omnisend offers you a number of options that you can use to review your emails’ design. You can use it to preview your message design, send a test email, or check the trigger automation workflow in real conditions. 

Previewing the design of your message is really straightforward and can be done right via its editor. Plus, you can also get a preview of how it will appear on desktop as well as mobile devices. What’s more, if you’re using it for mobile previews, you can even change the screen layout by using the rotate option. 

Just like GetResponse, it also offers more than just email testing and includes A/B testing functionality among others. With its A/B testing feature, you can divide your subscribers randomly into two groups and test the impact of different subject lines and message content. 

Pricing: It offers a Free plan and two paid plans with pricing starting at $16 per month. 

Omnisend is an all-in-one email marketing automation platform. It particularly targets high-growth eCommerce businesses. You can integrate channels into your automation workflows, send personalized me...

2. GetResponse


A/B testing is a key step when running your email marketing campaigns. Meet GetResponse. 

You can use it to run tests and find out which actions to take next. You can, for example, use it to A/B test subject lines and adjust them based on open rates. It also offers powerful analytics for all your email marketing campaigns helping you to analyze important email metrics like open rate, click-through rate, and unsubscribers. 

It’s much more than just a tool for the occasional testing, though. In addition to its long list of email marketing features, it also includes landing pages, signup forms, and a new website builder. 

Pricing: It offers a Free plan and three paid plans. Pricing starts at $19 per month, after a free 30-day trial. 

GetResponse offers a powerful, simplified tool to send emails, create pages, and automate your marketing. It focuses on email marketing, landing pages, marketing automation, and conversion funnels. It...

3. Litmus


Litmus is one of the top email marketing automation tools and is trusted by over 700,000 users, including the likes of Ford, Booking.com, and Target. They make building, testing, and analyzing emails as easy as sending an email and, according to their website, they can help you to reduce the time that you spend on email testing and quality assurance by half.  

From email preview testing to spam testing, Litmus offers a suite of tools that can help you to test various elements. Not only can you use it to preview your campaigns instantly across 100+ popular email clients, but it will also share actionable suggestions based on their data to help you optimize your email design further. 

Pricing: Pricing starts at $99 per month when billed monthly. 

4. PutsMail


PutsMail is another tool powered by Litmus that you can use to test HTML emails before you send them. It was originally designed by a software developer based in Brazil, but was bought three years later by Litmus that developed it further to offer it as a free standable tool to email marketers. 

If you don’t want to sign up for the complete Litmus testing suite, this is a good place to start. All you need to do is add an email address that you own and control, a subject line, a plain text version of your email as well as the HTML part. 

Pricing: Free

5. Email on Acid

Email on Acid

Email on Acid is a comprehensive-automated email pre-deployment platform and one of the leading email testing platforms. Trusted by developers, marketing teams, and enterprise organizations that include names like Toyota, IBM, and KLM, their time-saving tools help you to protect your brand name, while improving marketing ROI. 

It offers various features that can help with previews, deliverability issues, and compliance. With the help of Email on Acid, there’s also no need to review your emails manually. Their Campaign Precheck can complete the work on your behalf, helping you to send out optimized, error-free emails quickly. 

Pricing: After a free 7-day trial, pricing starts at $99 per month when billed monthly. A custom enterprise package is also available upon request. 

6. GlockApps


GlockApps initially started out as simply a spam testing tool, but has expanded their focus to create a comprehensive solution for email deliverability to include four tools: Inbox Insight, DMARC Analytics, Bounce Tracker, and IP Reputation Monitor. 

If you’re only interested in finding out where your emails end up, you can still use it free of charge as it offers an easy-to-use, free email inbox tester. For more functionality, you’ll need to sign up for one of its paid tools, though. For example, its Inbox Insight will give you a deliverability report which includes your spam score and itemized feedback.  

Pricing: In addition to a Free plan, they offer three paid plans with pricing starting at $79 per month when billed monthly. 

7. TestSubject


An email testing tool that you should definitely have in your arsenal is one dedicated to subject lines. Your subject line is one of the most critical elements. It helps to capture attention and urge subscribers to open your email. Just like your human readers use it to decide if it’s worthy of their time, spam filters also turn to subject lines when labeling emails as spam. So, there’s a lot that hinges on those few words. 

TestSubject by ZURB is one of the best subject line tester tools to check out if you know that most of your audience read their emails via mobile devices. It’s a simple tool that you can use to test how your sender name and subject line will appear across popular mobile devices and email clients. What’s more, you can also use it to preview your preheader text. 

All you need to do is type in your sender name, subject line, and preheader text. It will instantly show you how these three elements will appear on different iOS and Android mobile devices.  

Pricing: Free

8. Email Subject Line Grader

Email Subject Line Grader

Email Subject Line Grader by Net Atlantic takes subject line testing further than just merely how it will display on various devices. It also gives you suggestions regarding wording to help you create more powerful headlines for your campaigns.

All you need to do is type in the headline you’re thinking about using and it will give you a score. It will also share suggestions based on the type of headline you can use, character count, and word count. 

Pricing: Free

9. Stripo


Stripo is better known for their wide range of email templates. In addition to their templates, they also offer an email testing tool that you can use to preview your message across over 70 devices and apps for compatibility. 

With the help of this new email preview feature, you can identify and fix potential problems before you hit send. Some of the issues that it can help to identify are missing alternative text for when images don’t load, custom fonts, call-to-action buttons, and background images. 

Pricing: While they offer a Free plan, the email testing feature is only available in one of their paid plans. Pricing starts at $15 per month. 

10. Mailtrap


Mailtrap offers impressive automation for testing email sequences. In addition to testing if emails are sent and delivered, it can automatically verify various other variables like email headers, sending triggers, spam scores, and attachments. 

Trusted by nearly 1 million users that include well-known names like Adobe, Calendly, and Yelp, it’s more than just a tool to preview your email in different email clients. There’s no need for manual comparison as it will explain how to resolve the issues immediately.

Pricing: Compared to other solutions, it offers much more flexibility with regards to pricing. In addition to a Free plan, there are five subscription plans to choose from. Pricing starts at $10 per month. 

11. Moosend


Moosend is one of the leading email automation software solutions. In addition to its various email marketing features, it also includes a free subject line tester, spam filter reports, and A/B testing. 

Of all the subject line testers, this one has to be one of our top picks. In addition to adding your headline, you also need to pick an industry from its drop-down menu and indicate to how many recipients you plan to send this email. It will then calculate the open rate you’ll likely generate and how it stacks up to the average open rates for your industry. 

What’s more, it will also share suggestions for how you can boost that open rate and by how much you can increase the original estimation if you were to implement their suggestions. For example, for our quick test it suggested that if we simply leverage email personalization by including the recipient’s first name, we could boost our open rate by over 6%. 

Pricing: After a free 30-day trial, pricing starts at $9 per month. 

12. Sender Score

Sender Score

While content plays a key role in the success of your campaigns, all your effort will be in vain if your reputation is a problem. And, by reputation, we don’t necessarily refer to how your brand is perceived. 

You also have an email sender score that you need to worry about. Think of it as a type of credit worthiness check for email that gives you an indication of how mailbox providers rate your IP address. This is done by taking into account several metrics like spam complaints.

To help you figure out where your sender reputation falls on the spectrum, all you need to do is enter your IP address and a few other personal details like how many emails per month you plan to send, your country, and name of your business. It’s free to sign up and you’ll get access to comprehensive reports and other free tools like a Blocklist Lookup. 

Pricing: Free

13. SendForensics


If you suspect there’s a problem with your sender reputation but you’re searching for a more comprehensive tool than Sender Score, you can check out SendForensics. It’s an all-in-one deliverability tool that you can use to check everything from previews to inbox placement and loads more. 

What makes SendForensics such a useful tool is that it has a reputation dashboard that makes it easy to keep track of your domain and IP reputation, while it will also automatically monitor any possible blacklist activity. As soon as they’ve spotted a potential risk, they will flag it so that you can sort it out before sending your next batch of messages. 

Just like GlockApps, it also includes DMARC monitoring. This way, you can take a proactive approach and identify people who are using your domain to send fraudulent emails that can damage your brand and sender reputation. 

Pricing: After a trial period of 14 days, pricing starts at $49 per month when billed monthly. 

      Wrapping Things Up

      Compelling emails can deliver one of the highest ROIs. To achieve this, though, there are various elements that need to work. 

      Sure, the content of emails matter a lot, but there are other more technical matters like email sender reputation that can also limit your success. While you have less control over certain things, handy tools like Litmus and Email on Acid can help you to identify where the problem lies. Ignorance might be bliss, but if you don’t know that you have a problem in the first place, how will you ever be able to improve your results?

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