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Top 12 email testing tools


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Written by Ashlie Jones
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Among the many processes involved in an email marketing campaign, email testing is usually ignored, which is such an irony. When you launch an email marketing campaign for your business, it makes sense to want to know how the campaign is running and performing. However, this process is often ignored because it tends to be a daunting task. Other times it could be due to a lack of suitable testing tools. 

If you can't evaluate the performance of your emails because you lack the necessary tools, this post will solve your problems. Below, we have singled out 12 of the best email testing tools in the market to help you send out winning emails. These tools can be used by email marketers, developers, and even QA testers. Read on and discover the ideal tool that fits your level of expertise. 


Subject line

The Subject Line is just that: a tool for testing email subject lines. You can use this tool to test the spam score and open rate of an email subject line. It helps you have a clearer picture of the value and direction of your subject line, plus insights on how to improve it. This tool has a vast capacity to gather, manage and analyze data. It's also a good email marketing resource. Not only is the Subject Line available for free, but it provides informative results, can improve email open rates, and keeps information safe and secure. The only downside is limited customer support since it's a free tool. 

Subject line screenshot



Litmus is an efficient marketing tool that you can use to create, test, and analyze all email service providers (ESPs). Litmus helps you predict the probability of an email not being delivered and why. Litmus has a user interface to load screenshots of your existing email recipients and email folders. It also features a Builder that you can use to check and test different codes against various email recipients so you can streamline your processes. 

From the user interface, teams can seamlessly share comments and receive editor feedback. Litmus works with various ESPs such as Acoustic Campaign, Oracle Eloqua, Salesforce Marketing, Adobe Campaign Standard, Pardot Adobe Marketo, Salesforce Marketing Cloud, HubSpot, Oracle Responsys, and SAP Marketing.

Litmus screenshot


MailTester is an email verification software that operates from the cloud. It helps users verify email domains and syntaxes. It has an easy-to-use interface ideal for beginners or users with limited technical knowledge. 

MailTester comes with an extensive toolbox, including Spam Trap Removal, which detects and traps spam emails in your email list. It also has a Syntax Verifier, which catches and removes emails with invalid syntaxes. MailTester provides both manual and automatic email verification and uses API to enable you to download segmented results. The MailTester comes in a free and paid version, with the paid version starting from $19/month per user.


Sender Score

Sender Score checks the reputation of an email sender. To use this email verification tool, you'll need to type in your IP address or domain name and receive reports on your trustworthiness as an email sender. 



HubSpot has a "Complete A/B Testing Kit," a combination of tools that you can use to brainstorm AB testing ideas, create AB tests and analyze the results. You'll find it highly intuitive, especially if you're getting started. HubSpot supports dynamic content creation; it's also optimized for mobile and provides data quality management. 

HubSpot can be customized to suit your business needs and has excellent end-user support. The user interface is intuitive and user-friendly. It's a free tool ideal for email marketing as it is kept up to date with the latest technology and marketing trends. 

HubSpot AB test screenshot


Mailtrap is an email sandbox service consisting of various testing tools for email verification,  spam score evaluation and 

HTML and CSS validation. Mailtrap is ideal for freelancers, SMBs, and enterprises. It has free and paid plans starting at $10/month.


Email On Acid

Email On Acid is a paid email testing tool for previewing email content to mitigate issues with spam filters. With Email On Acid, you can run domain blocklist checks to increase your email deliverability. Additionally, you can maximize its engagement tracking options to monitor your subscribers' interactions. It's suitable for agencies, SaaS companies, and large businesses. Email On Acid has a 7-day trial and paid plans starting at $86 per month.



Send Forensics is an email testing service that contains a combination of testing tools to help you increase your email deliverability. You can use this tool to view your sender score, preview your email content and improve your email marketing campaign to avoid spam filters. Its features include:

  • AI-driven data
  • Inbox placement testing
  • Comprehensive content analysis and optimization
  • Infrastructure auditing

The disadvantage of SendForensics is its glitchy fog items and low customer support. Otherwise, it has a free version that allows you to scale up to a paid plan of $49 for two domains.


Email Checker

Email Checker is straightforward software for checking the validity of an email address. All you have to do is copy and paste an email address in the required field to verify its validity. However, it has a free version that's only good for checking limited emails, not bulk ones. Email Checker works the same way as Email List Verify. To mean that for bulk emails, you'll need the paid plan.

Email Checker Screenshot


Clearout performs both email validation and verification with an accuracy of 98 percent. Its features include affordable pricing, fast turnaround time, accurate results, and compatibility with any device. However, its integration with other ESPs is limited, and it provides few free credits. It is a paid plan with 5,000 credits costing $20 per month. You can receive a 30% discount if you make an annual subscription.



NeverBounce is yet another powerful email verification tool that helps you maintain a clean, valid email list. Some of its benefits include automated list cleaning, you can connect your email provider with the program for automated email verification, ensuring continuous accurate and up-to-date data.

Other interesting features NeverBounce has are bulk email list cleaning, and last but not least, real-time email verification.

With real-time email verification, emails will be checked as they are entered into your forms, preventing invalid email addresses from reaching your contact list.

Overall, it is a great tool to avoid high hard bounce rates caused by sending emails to invalid email addresses.


Zero bounce

Zero Bounce helps you establish if the emails you send will reach the recipient's inboxes. It helps you declutter your email list since it is a verifier of bulk emails. Additionally, you can link

ZeroBounce's API to your newsletter sign-up forms and run real-time checks. You can also use Zero Bounce to perform email deliverability tests and discover server issues. ZeroBounce is suitable for individuals, SMBs, SaaS, and enterprises.



Emails are vital for the success of your marketing campaign. By conducting comprehensive email testing, you can improve your email efficiency, deliverability, and success rates. The best way to achieve this is by working with suitable email testing software. This guide provides a list of the top 12 best email testing tools that you can work with.

Whether free or paid, most of these tools are effective and guarantee better results. Once you've settled on the one that meets your business needs, the next step is to download our guide to email marketing best practices

Button to download Email Marketing Best Practices guide.