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There are seemingly countless email testing tools available, so figuring out which is best for you is tough. You want to optimize your emails for maximum deliverability and engagement but need to figure out which tool is the best fit. I've got you! In this post I make things simple, leveraging my experience using dozens of different email testing software to bring you this shortlist of the best email testing tools.

What Are Email Testing Tools?

Email testing tools are software used to evaluate and optimize email campaigns before they are sent. These tools test various elements of emails, including layout, content, links, and compatibility with different email clients and devices. They check for potential deliverability issues and help in ensuring that emails appear as intended in the recipient's inbox.

The benefits and uses of email testing tools include improving the deliverability of emails by identifying and fixing issues that could trigger spam filters. They ensure that emails render correctly across various platforms, enhancing the recipient's experience. These tools also aid in optimizing email content for better engagement, such as through effective subject lines and functional links. By using email testing tools, marketers and communicators can achieve more professional and effective email communication, leading to better campaign performance.

The 10 Best Email Testing Tools Reviews

Here’s a brief description of each email testing platform to showcase each tool’s best use case, some noteworthy features, and screenshots to give a snapshot of the interface.

Best for creating & testing email templates

  • Free version available
  • From $12.50/month
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Rating: 4.8/5

Stripo is an email design platform that allows teams to design responsive emails with little or no HTML skills required. It is equipped with a comprehensive drag-n-drop editor and a set of basic blocks that allow users to create real-time content with no coding skills. Stripo was one of the first email builders to implement AMP for Email technology.

Stripo allows you to reuse and save email modules, even across different email campaigns. It comes with automated processes, custom modules libraries, and provides a host of personalization like the ability to embed custom HTML code to create interactive elements.It provides users with over 1000 free and ready-to-use responsive email templates that are also mobile optimized.

Stripo comes with over 100,000 stock images along with the opportunity to personalize and export emails, then track conversions thereafter.Stripo can be integrated with over 60 ESPs/CRMs tools. This provides users with versatility and flexibility of functionality, for instance, to push emails to automation systems with only a click of a button.

Best for email testing in staging environments

  • A free version specifically for a single inbox and up to 500 email tests per month.
  • From $9.99/ month for 1 user and up to 5 inboxes
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Rating: 4.8/5

MailTrap is an online tool for safe email testing in development and staging environments. The tool is used as a fake SMTP server to catch test emails, view them in virtual inboxes, and debug before they are sent to real users. MailTrap allows you to test and iterate over new emails efficiently in order to avoid emails mistakenly being sent to clients and other employees from dev environments. MailTrap can be integrated via API or as an SMTP server.

MailTrap offers numerous features, including Bcc testing. Most email testing tools do not support Bcc as it is not a regular SMTP header like To or Cc. MailTrap displays all Bcc’ed addresses and is able to verify whether they stay invisible for the main recipients. MailTrap also provides a customizable email address for each inbox, allowing you to run tests in a production environment in addition to a development environment.

Best for testing email accessibility

  • From $74/month
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Rating: 4.5/5

Email on Acid is an email platform that specializes in quality assurance and pre-deployment functionality. It enhances organizations’ ability to deliver error-free emails that maintain brand reputation to ultimately boost marketing ROI.

Email on Acid strives to provide consistency in visual email rendering across different devices and platforms, ensuring generated emails get displayed as intended. It streamlines the email testing and pre-deployment process with campaign prechecks, URL validation, image optimization, and so on.

Email on Acid allows you to run checklists that matter like UTM validation and ADA compliance.Email on Acid improves email deliverability rates with spam checks in addition to providing access to blacklisted domains. This allows developers and email designers to verify their email list against up to over 20 popular spam filters while also testing IP addresses against popular block list services.

Email on Acid comes with an editor for building templates along with team collaboration tools for better efficiency.

Best for app developers

  • Free to use

MailHog is an email testing tool with a fake SMTP server that is designed specifically for app developers. The tool allows you to configure your application to use MailHog for SMTP delivery, view messages in a web UI, or retrieve them with the JSON API, and optionally release messages to real SMTP servers for delivery.

MailHog is a lightweight tool that you do not have to install, therefore it can be run on multiple

operating systems, including Windows, Linux and MacOS. This allows easy access for developers to test web app’s email sending and receiving capabilities. MailHog also provides real-time updates using an EventSource web interface. Captured emails can be stored in in-memory message storage and persisted in a MongoDB database and file-based stored system.

Best free email testing tool

  • Free to use

MailCatcher is an email testing tool that is designed to intercept all mail from any web or mobile app and store it for display. MailCatcher runs a fake SMTP server and shows HTML and CSS emails, Plain Text emails and Source versions of messages as applicable. It also rewrites HTML enabling display of embedded images and can open links in a new window. This allows you to effectively test all aspects of your email and check the formatting before it goes to your client.

MailCatcher mail appears instantly if WebSockets is supported on your browser, otherwise it updates every thirty seconds. It also offers command line options to override the default SMTP/HTTP IP and port settings, which allows you to manipulate your testing the best way for your practice.

Best for integrations

  • 7-day free trial
  • From $79/month for the basic package

Litmus ESP is an email marketing tool that helps you build, test, and analyze all email service providers (ESPs). Litmus allows you to chart the specific reasons why an email may fail to deliver, as well as allow you to see the time taken to load an image and have accessibility to real world processing into inboxes.

Litmus’s user interface provides fast loading screenshots of all current email clients, organization of emails within one folder system, preview testing of email content and a Builder for checking and testing various code against different email clients, allowing you to streamline your processes. The user interface also allows for team commenting and editor functionality.

Litmus connects with a wide range of ESPs and other services, including Acoustic Campaign, Adobe Campaign Standard, Adobe Marketo, Hubspot, Oracle Eloqua, Oracle Responsys, Pardot, Salesforce Marketing Cloud, and SAP Marketing Cloud.

Best for email + web monitoring

  • Free Trial
  • $39/month for 10 test targets at 1-min frequency

Wormly is a website uptime monitoring solution that tracks things like site uptime, CPU usage, and SMTP server testing for new mail servers. You can access SMTP testing and Remote Ping testing for free through their site by adding a few details into an on-page form. Wormly provides detailed website and app uptime reporting and runs on all major operating systems including Windows and Linux.

In addition to email testing, Wormly offers a website monitoring service which continually monitors your website infrastructure and will alert you if a failure is detected, allowing you to act quickly and minimize downtime. The tool also offers sensors to monitor TCP/IP services to their full extent which allows you to get a picture of your infrastructure availability and uptime.

Best for marketing automations

  • From $14.99/month; then, add $20/block (AKA 25,000 emails)

Mailchimp is an all-in-one marketing platform with a robust content creation suite, marketing analytics, and add-on options for advanced email testing features. Mailchimp is AI-powered and provides user-friendly tools on an intuitive user interface, offering accessibility to users who lack deep technical knowledge. Mailchimp offers comprehensive reporting for deliverability, open rates, click-throughs, and conversions.

Mailchimp provides marketing automation features so you can manage transactional deliveries and automate tasks and communications. The tool is scalable, allowing you to send a large quantity of emails at once. Mailchimp also offers website hosting and design, making it easy for the user to create landing pages from a variety of basic templates (or code your own from scratch).

Best for ease-of-use email testing

  • Free trial available
  • From $19/month for 1 user

MailTester is a cloud-based email verification solution that helps businesses verify the domains and syntax of emails. The tool is an effective first line of defense for email testing and provides an easy to use user interface, allowing accessibility to users lacking technical knowledge.

MailTester offers an extensive toolbox which includes Spam Trap Removal (searches for spam trap emails in your email lists) and Syntax Verifier (catches emails containing invalid syntaxes and deletes them). MailTester allows manual as well as automatic email verification using API and allows you to download segmented results.

Best for end-to-end email testing

  • 7 Days Free Trial
  • $21.66/month (billed annually)

MailSlurp is an “email as a service” tool with email sandbox APIs, deliverability dashboards, auto-forwarding, webhooks, and inbox routing that is used by the likes of Trivago, Ring, and Panasonic.

Using REST API, the tool allows you to programmatically test transactional emails and fundamental user engagement by sending actual emails to real email addresses to your application. Used primarily by developers and QA testers, MailSlurp allows you to create real inboxes on demand, send and receive emails and attachments in code, and tests using a variety of frameworks and languages such as Selenium and Jest.

MailSlurp uses a custom SMTP MailSErver and AWS SES to send and receive your emails at scale. You can send contact groups email design templates and track the number of times an email has been opened using actual email addresses, test user authentication, forgotten passwords and email verification.

The 10 Best Email Testing Tools Summary

Tools Price
Stripo From $12.50/month
Mailtrap From $9.99/ month for 1 user and up to 5 inboxes
Email On Acid From $74/month
MailHog Free to use
MailCatcher Free to use
Litmus ESP From $79/month for the basic package
Wormly $39/month for 10 test targets at 1-min frequency
MailChimp Transactional Email From $14.99/month; then, add $20/block (AKA 25,000 emails)
MailTester From $19/month for 1 user
MailSlurp $21.66/month (billed annually)
Preview Image - <h2 class="c-block__title b-summary-table__title c-listicle__title h3" > Compare Software Specs Side by Side</h2>

Compare Software Specs Side by Side

Use our comparison chart to review and evaluate software specs side-by-side.

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Other Email Testing Tools To Consider

Here’s a few more that didn’t make the top list.

Selection Criteria For The Best Email Testing Tools

What do I look for when I select the best email testing solutions? Here’s a summary of my evaluation criteria:

  1. User Interface (UI): I look for user-friendly and clean dashboards. A pleasant user experience goes a long way, ensuring everything is clear, concise and organized.
  2. Usability: I look for effective but easy to use platforms with extensive documentation for reference and training.
  3. Integrations: I look for easy and efficient email integration opportunities. These include various social media platforms, email providers such as Gmail and Outlook, and analytics that are easily executed.
  4. Value for $: I look for what features and access levels you get for your money. Is it worth what you’re paying?

Email Testing: Key Features

  1. Email Integration: Email testing tools should work with all the most popular email providers. These include Gmail, Outlook, AOL, iCloud, and so on.
  2. Spam Tests: Email testing tools should be able to detect whether or not your email campaigns can make it through common spam filters.
  3. Sender Score: The software should give you an idea of your sender score. In other words, how likely you are to be able to make it in front of your target audience.
  4. Defect tracking: If a problem arises, the tool should appropriately flag and log it. This means that your team can address it in a timely fashion.
  5. Deliverability optimization: The platform should provide insights that improve your likelihood of emails reaching their target destination.

FAQs About Email Testing

Still have questions about email testing in general, and email testing tools specifically? I’ve answered some common questions on this topic for your convenience:

What are the common challenges in email testing?

Email testing is always becoming more advanced and nuanced. Some challenges are old and familiar, while new ones are cropping up all the time. Here are a few you may have run into (or might in the future):

  • Render variability: Different email clients render in HTML/CSS differently. Formatting might look different on Outlook vs. Gmail vs. Apple Mail.
  • Responsive designs: Designs can show up differently on different devices like Android or iOS mobile devices, desktop, and tablet.
  • Spam filters: Your perfect email is useless if it lands in the spam folder, but it’s not always clear how to craft email content and email designs that won’t get filtered out.
  • Attachments & links: These can trigger spam filters or not work as intended. It’s important to take extra care when including links or attachments.
  • Email size: An oversized email can slow down loading or display incorrectly. Keeping it lean while maintaining quality is the goal.
  • Plain text vs. HTML: Making sure both versions exist and are in sync is sometimes overlooked. Yet, it’s foundational for accessibility and deliverability.

These are just a few factors that can impact your email deliverability, functionality, conversion rates, and more. Using an email testing tool can help you weed out risks or errors and overcome these common challenges.

How do email testing tools improve deliverability?

Email testing tools help you address a number of the challenges listed above, in turn improving your email deliverability. Here are a few ways these tools address deliverability issues:

  • Spam filters: These tools emulate various spam filters from popular email service providers, and some even serve up a spam score with actionable tips to bring it down.
  • Email previews: Avoid visual glitches in your emails by seeing how your designs look across multiple email clients, operating systems, and devices.
  • Link validators: Many tools will check for broken links, ensuring the user’s path is clear.
  • Load time analyzer: These tools can gauge email size and loading speed, helping you trim the fat as needed.
  • Authentication checks: SPF, DKIM, DMARC – the trio of email legitimacy. Tools validate these, ensuring your emails are seen as friends, not foes.
  • A/B testing: Many tools support email subject line testing and segmentation of email delivery time, among other A/B tests.

All of these features and functions of email testing tools help you improve deliverability, open rates, and conversions. They can even help you grow your subscriber list and activate inactive subscribers.

How do I measure the ROI of using an email testing tool?

Before you invest in a new tool (or convince your boss to invest in one), it’s important to figure out your goals for how you’ll use it, and how you’ll measure success. In 6 months time, you’ll want to be able to show that there’s been a return on the investment.

The good news is that most of these tools provide email analytics and reporting features to help you measure and track key email metrics. Here are a few ideas of how to measure the ROI of your email testing tool:

  • Deliverability rate increase: Measure your email deliverability before and after tool implementation. Improved deliverability directly links to potential revenue upticks.
  • Email engagement metrics: Observe changes in open rates, click-through rates, and conversion rates post-testing. Positive shifts? The tool’s doing its job.
  • Bounce rate reduction: A declined email bounce rate post-tool adoption indicates better email list health and targeting. This translates to saved costs and increased opportunities.
  • Time saved: Manual testing can be gruelling. Calculate work hours saved post- versus pre-tool days and quantify that in monetary terms.
  • Error costs avoided: Track the number of errors tools catch before going live. Estimate potential brand damage, lost sales, or customer service time for each error and sum it up.
  • A/B testing results: If tools help in A/B testing, calculate the difference between the two versions in monetary terms.

Finally, be sure to measure the other side of the equation. Deduct the tool’s cost from the gained value (from the points above) to get a clearer ROI picture.

Email Testing Is A Top Priority!

Ensuring emails are signed, sealed, and delivered effectively is so important, and QA specialists should absolutely care about email testing. Email verification processes can improve everything from your sender reputation to your DMARC analytics. And setting up an email testing tool is a great place to start.

In fact, failing to run proper email testing can lead to a range of consequences. These range from not hitting your marketing strategy KPIs to facing serious legal troubles. So leverage the tools on this list to keep your email sending above board!

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Paulo Gardini Miguel
By Paulo Gardini Miguel

Paulo is the Director of Technology at the rapidly growing media tech company BWZ. Prior to that, he worked as a Software Engineering Manager and then Head Of Technology at Navegg, Latin America’s largest data marketplace, and as Full Stack Engineer at MapLink, which provides geolocation APIs as a service. Paulo draws insight from years of experience serving as an infrastructure architect, team leader, and product developer in rapidly scaling web environments. He’s driven to share his expertise with other technology leaders to help them build great teams, improve performance, optimize resources, and create foundations for scalability.