The 18 Best Email Testing Tools You’ll Need In 2021 [Free & Paid]

Getting your campaigns through email testing tools is no longer optional but a necessity for every modern marketer.

Crafting converting email campaigns that pass spam filters sounds like a dream. However, to achieve it, you need to test your messages to ensure that your subscribers will have the best possible experience with your business.

Today, we’ll explore 18 different tools to help you:

  • preview your email design
  • power up your email deliverability
  • A/B test your campaigns
  • verify your email lists
  • optimize your subject lines

Without further ado, let’s see the best paid and free email testing tools you’ll ever need.

Email Testing Software: Comparison Table

Before we start, here are the best email testing platforms you can find out there, organized per category.

Testing SoftwareFree PlanPricingUnique FeatureRatings
Email Preview & Spam TestMoosendYes(Sign up here)$8/monthDesign and delivery tests
SMTP Server TestingSocketlabs Yes$39.95/monthBounce processing option
Email Deliverability CheckGlockAppsYes$79/monthSender reputation check
Email ValidationZeroBounceYes$16/monthQuality contact scoring
A/B TestingVWO30-day free trialUpon requestMultivariate email tests
Email Subject Line TesterHeadline StudioYes$19/monthHeadline scoring

As you’ll see below, the list contains numerous options you can choose from. But to choose the best one, always consider the following criteria:

  • Price
  • Features
  • Useability

While a free tool might sound ideal, especially for SMEs with tight budgets, investing in paid email testing solutions might actually save you more time and money.

Now let’s see the best of the best for each category:

Email Preview & Spam Test Tools

The first thing you need to avoid the spam folder is to make sure that your emails display correctly in the inbox. For that, you’ll need robust HTML validation and preview tools to make sure everything looks good:

1. Moosend – Design, Delivery & Content Spam Test

Pricing: Free-forever plan (sign up here), paid plans start at $8/month

Best for: SMEs, eCommerce, SaaS, Publishers, Bloggers

email testing tools

First of all, Moosend is an email marketing service that offers you the tools to craft, automate, test, and send your email campaigns.

Apart from its email creation, lead generation, and email list management capabilities, the platform will give you access to design and delivery testing features to make sure that your messages look good before they reach the inbox. This is useful for marketers who use the HTML builder and want an easy way to check their campaign and pre-send it to their testing email addresses.

On top of that, the platform will let you generate spam filter reports to see how your messages rate against popular spam filters including Outlook, Gmail, and Yahoo.

Best Email Service Features

Moosend Pricing

The email service provider (ESP) has a free forever plan to send unlimited email marketing campaigns for up to 1,000 subscribers. Free users can take advantage of the email testing tools at no cost. For additional features, paid plans start at $8/month giving you access to the SMTP server, landing pages, and more.

Register now

2. Mailtrap – HTML/CSS Validation Tool

Pricing: Free plan, paid plans start at $10/month

Best for: Freelancers, SMBs, Enterprises

mailtrap preview test software

Mailtrap is an email sandbox service with a variety of testing tools to help you analyze your email campaign copy, discover your spam score, and validate your HTML and CSS.

The software allows email marketers to detect how many of their recipients will emails that are displayed correctly for different email clients. Moreover, Mailtrap makes it easy to identify problems in your HTML code and catch potential design or formatting issues before they harm your engagement and delivery rates.

Lastly, you can use the platform to check for potential rendering errors between desktop, mobile, and tablet devices.

Best Testing Software Features

  • HTML email validation tool
  • Email client support verification
  • Audience optimization
  • Email preview for different devices
  • Shared virtual inboxes

Mailtrap Pricing

Mailtrap has a free version for up to 500 email tests per month. To increase the limit, you will need to upgrade to a paid plan starting with the Individual at $9.99/month, the Team at $24.99/month, and the Business at $49.99/month. Premium and Enterprise plans are available.

3. Email on Acid – Email Preview & Validation

Pricing: 7-day trial, paid plans start at $86/month

Best for: Large Businesses, Agencies, SaaS

email on acid email testing tools

Email on Acid is among the paid email testing tools you can use to preview your email content and discover which elements might cause your trouble with spam filters.

When it comes to previewing, the platform sports an array of features to help you nail your test emails, including sharing, approvals, and commenting. Apart from its content email testing options, Email on Acid allows you to perform domain blocklist checks to improve your email deliverability.

On top of that, you can benefit from its engagement tracking options to be up to date with your subscribers’ interactions.

Best Email Optimization Tool Features

  • Image validation
  • Inbox display feature
  • Email accessibility options
  • Pre-header text test
  • Team management

Email on Acid Pricing

You can try the platform by signing up for the available 7-day trial. Then, you can upgrade to the four different paid plans, including the Basics at $86/mo, the Premium at $132/mo, and the Professional at $499/mo or the Enterprise (custom price).

SMTP Server Testing Tools

If you’re interested in keeping your inbound and outbound email sending problem-free, you need to get your hands on an SMTP Server testing tool. Here are some great options to consider:

4. SocketLabs – SMTP Checking Software

Pricing: Limited free plan, paid plans start at $39.95/month

Best for: Marketers, eCommerce, Large businesses

socketlabs smtp testing tools

Socketlabs is a great option for testing your SMTP relay service, giving users easy configuration options, reporting tools, a dedicated IP address, and a lot more.

With the platform, you can send marketing and transactional emails either by integrating the tool with your apps or through Socketlabs’ Control Panel.

What’s more, the tool is great for improving your email delivery through its advanced reporting capabilities. More specifically, you will have access to detailed reports showcasing failed messages, deliverability issues, engagement, and more.

Best SMTP Testing Platform Features

  • Deliverability insights
  • StreamScore™ delivery reporting
  • Automatic bounce processing
  • Dedicated IP address
  • Reporting API

Socketlabs Pricing

This SMTP testing tool has a free forever plan for 2,000 emails per month and a free trial of the Basic Plan. After the 30-day free period, pricing starts at $39.95/month. For more, you can upgrade to the Professional plan for $79.95/month or talk to an expert regarding the High Volume Custom plan.

5. MxToolBox – Mail Server Testing Tool

Pricing: Limited free plan, paid plans start at $99/month

Best for: Agencies, SaaS, Enterprises

mxtoolbox smtp email testing platform

MxToolBox’s delivery service is equipped with a variety of tools to help you identify potential issues and improve your SMTP Server security.

The platform will also help you keep track of your MX record, DNS, blacklists, and SMTP analytics. All you have to do is to add your domain name, your IP address/hostname and you are ready to roll.

Apart from that, MxToolBox’s super tool will allow you to run a variety of tests, including HTTP/HTTPS verification, SPF and TXT record check, ICMP pinging and trace routing, and DNS server trouble-shooting.

Best Email Testing Tool Features

  • Mail server testing
  • Real-time deliverability insights
  • Blacklist monitoring
  • Inbound and outbound Mailflow monitoring
  • Email Health check option

MxToolBox Pricing

MxToolBox offers a limited free plan that gives you 1 blacklist monitor, blacklist checks every 7 days, and 30 blacklists checked. For access to the premium features, you have to upgrade to the Delivery Centre plan starting at $99/month or the Deliver Centre Plus plan at $399/month.

6. Wormly – Uptime Monitoring Platform

Pricing: Free trial, paid plans start at $39/month

Best for: Agencies, Marketers, Developers, Enterprises

wormly email testing tools

Wormly’s email testing tool focuses on monitoring your uptime and metrics to help you minimize your downtimes and increase your revenue.

To achieve it, the tool is designed to give you instant failure alerts through SMS, Slack, etc., to help you act fast. What’s more, you will have access to all protocol monitoring, including HTTPS, POP3, IMAP, FTP, and so on.

When it comes to running an SMTP test, you only need to add your Hostname or IP, your email address, and your TCP port and you are ready to start.

Best Email Testing Software Features

  • SSL web server test
  • SMTP server testing tool
  • Advanced metrics (Apache, PHP-APC, etc.)
  • Performance trends
  • Uptime reporting

Wormly Pricing

Wormly has a free trial you can try, giving you access to 5-second High Definition monitoring, HTTP POST & SSL cert. Monitoring and more. If you want more, you need to upgrade to a paid plan starting with the Startup at $49/month, the Agency at $95/month, the Devops at $195/month, and the Enterprise at $495/month.

Email Deliverability Test Tools

To avoid the spam folder you need to pay attention to your email deliverability in order to maintain an excellent sender reputation and sender score. Below, we’ll see a few handy tools to achieve it:

7. Mail Tester – SPF & DKIM Testing Service

Pricing: Free to use

Best for: Individuals, small businesses with tight budgets

mail tester email deliverability testing software

Mail Tester is a free-to-use tool that you can use to test your email deliverability. Users can instantly check their email campaigns for any issues and receive their score in a couple of seconds.

What’s more, the tool is great for checking your SPF (Sender Policy Framework) and DKIM (Domain Keys Identified Email) records, test your mail server, IP address, and identify spam-related content that will harm your email delivery.

If you’re looking for more tools like this, make sure to check our email spam checker post!

Best Email Deliverability Service Features

  • SPF & DKIM testing option
  • IP address verification
  • Mail server testing
  • Configuration reports
  • SpamAssassin collaboration

Mail Tester Pricing

As mentioned above, Mail Tester is a free email testing software you can use simply by visiting their website.

8. Spam Check by Postmark – Email Delivery Tool

Pricing: Free to use

Best for: Bloggers, Marketers, SMBs

Spam check by postmark

While Postmark is an SMTP email delivery service, it comes with a few handy email testing tools to help you detect potential issues using SpamAssassin.

The platform will give you access to its Spam Score Checker for free. You can easily run your tests by adding your email code into the tool and take advantage of the JSON API to connect spam score processing in your applications.

If you want to take advantage of Postmark’s platform as an SMTP relay service you will have to get one of the available paid plans.

Best Free Spam Testing Features

  • Lightweight JSON API
  • SpamAssassin score
  • Spam score processing
  • Easy-to-use interface

Spam Check Pricing

You can use Postmark’s Spam Check tool for free. If you need additional features, you might want to consider using it along with other email deliverability tools found in this list.

9. GlockApps – Email Deliverability Tester

Pricing: Limited free plan, paid plans start at $79/month

Best for: SMBS, eCommerce, SaaS

glockapps email delivery testing tool

Next on the list is GlockApps, a tool that will help you identify common email issues, test major internet service providers (ISPs), and, ultimately, increase your open rates.

The platform is equipped with numerous features to help you land your emails in your subscribers’ inbox, from inbox insights and DMARC analytics to uptime monitoring and bounce tracking.

Lastly, GlockApps comes with a Domain Checker that you can easily use to protect your domain from malevolent use and shield your business from spoofing attacks.

Best Email Test Tool Features

  • Inbox email tester and insights
  • Bounce analytics
  • Sender reputation tests
  • Domain check tool
  • Email template editor

GlockApps Pricing

GlockApps has a Personal Free Plan for 3 email spam tests, 10,000 DMARC messages, as well as 10 uptime and Reputation Monitors (2 weeks trial). Then, pricing starts with the Basic Plan at $79/month and the Business at $129/month. A Custom Plan is also available.

Email Address Verification Tools

Verifying your email lists will allow you to maintain good list hygiene and help you remove questionable email addresses that might lower your sender score. Here are some amazing tools to make it happen:

10. ZeroBounce – Email Validation Service

Pricing: Limited free plan, paid plans start at $16/month

Best for: Individuals, SMBs, SaaS, Enterprises

zerobounce email verify app

ZeroBounce is among the popular email verification tools you can try to make sure that your emails will reach your recipients’ inboxes. The service is perfect for cleaning your email lists by running them through the bulk email verifier.

On top of that, you can easily connect ZeroBounce’s email validation API with your newsletter signup forms to perform real-time checks that will save you valuable time.

Apart from email validation, the email testing tool offers additional features to run email deliverability tests and detect mail server errors.

Best Email Verification Platform Features

  • Email Verification Tester
  • Quality scoring for contacts
  • Email deliverability test option
  • Blacklist monitoring
  • Email validation API

ZeroBounce Pricing

ZeroBounce sports a free plan for up to 100 emails. If you need more, you’ll need to upgrade to a paid plan starting at $16/month for 2,000 emails and so on. For over 2M campaigns, the service has a custom Enterprise plan.

11. MailFloss – Email Address Verification Tool

Pricing: 7-day free trial, paid plans start at $17/month

Best for: SMBs, Marketers, Large Businesses

mail flow email verification testing software

Mailfloss will enable you to “floss” your email lists from harmful or fake email addresses. To do it, the service lets you connect with your favorite email platform to remove invalid contacts and maintain a good sender reputation and sender score.

The tool is also perfect for newbies as it requires zero coding knowledge. Nevertheless, if you are more on the tech side, you can benefit from Mailfloss’ real-time API.

For more traditional users, you have the option to upload your spreadsheets or add email addresses manually.

Best Email Address Checker Features

  • Automatic daily cleaning
  • Real-time API
  • Invalid address auto-removal
  • Detailed analytics and stats
  • Integration with popular ESPs

Mailfloss Pricing

Mailfloss doesn’t have a free plan but offers a 7-day trial you can try out. After its expiration, you need to upgrade to one of the three available plans, the Lite at $17/month, the Business at $49/month, or the Pro at $200/month.

12. EmailListVerify – Email Verification Software

Pricing: Limited free plan, paid plans start at $139

Best for: Agencies, SaaS, Enterprises

emaillistverify validation testing service

EmailListVerify will assist you in validating your email list addresses. All you need is to upload your contacts (accepted formats include CSV, XLS, TXTX, etc.) and in a few minutes you can download a clean list that won’t damage your email deliverability.

Apart from its list verification abilities, the platform is capable of validating your SMTP server and domain, run spam checks, and perform MX record tests to increase your email ROI and help you succeed.

Best Email Testing Service Features

  • Email health checker
  • Blacklist tests
  • MX lookup
  • Email address extractor
  • SMTP server validation

EmailListVerify Pricing

EmailListVerify gives you 100 free email verifications when you sign up for the free plan. Then, you can choose between the Pay-as-you-go plan or get a monthly subscription starting at $139/month for 5,000 emails, $238/month for 15,000 emails, and so on.

A/B Testing Software

Performing regular A/B tests on your email campaigns is crucial for scaling your email marketing efforts. While the majority of email marketing platforms like Moosend and Mailchimp offer A/B testing, here are a few extra tools to help you out:

13. VWO – Multivariate Testing Platform

Pricing: 30-day free trial, available paid plans (upon request)

Best for: SMEs, Marketers, Engineers

vwo a/b testing tool

VWO is one of the most popular email testing tools in the market regarding split and multivariate testing. This means that you can A/B test any element of your email campaign and measure the performance of your new variants.

Marketers can easily launch new tests through the point-and-click editor to increase their email open rates and find the winning campaign versions. Compared to other tools, this testing software will let you run multivariate tests.

This means that you can try numerous combos to find what works best for your audience!

Best A/B Testing Tool Features

  • Email split test options
  • Point-and-click visual editor
  • Ready-to-use widgets
  • AI copy generator
  • Segmentation-based tests

VWO Pricing

VWO has a 30-day free trial you can check out. After that, you can grab one of their three available plans, the Growth, Pro, or Enterprise. To check their prices, you need to contact their sales team.

14. Optimizely – Experimentation Platform

Pricing: Limited free plan, available paid plans (contact sales)

Best for: SMBS, Non-profits, online stores

optimizely split testing service

Optimizely is another testing platform that you can use to run concurrent experiments that will improve your marketing plan.

The platform sports an advanced set of tools to experiment on different elements to optimize your messages and increase your overall engagement.

Apart from your email A/B Tests, Optimizely will give you the means to test your website through their visual editor. This way, you can try different UI variants to personalize your website messages and convert more visitors.

Best Split Test Service Features

Optimizely Pricing

Optimizely offers a Free Rollouts plan where you can get started with feature flagging and experimentation. To access the Full Stack or Web tools, you need to upgrade to one of their respective paid plans, the Accelerate or Scale by requesting a quote.

15. Mailchimp – Email A/B Testing Software

Pricing: Limited free plan, paid plans start at $15/month

Best for: eCommerce, Publishers

mailchimp a/b test service

Mailchimp is a famous email marketing tool that you can use to A/B test your email campaign before it hits your recipient’s inbox.

More specifically, the platform offers advanced tools to test various campaign elements (up to 3) like your content, subject lines, design, formatting, and more. Moreover, there’s also a Multivariate feature but it’s only available for Premium users, letting you test up to 9 variations.

Not a fan of Mailchimp? How about trying Moosend’s email service and A/B Testing tools instead?

Give it a try

Best Email Testing Tool Features

  • Multivariate testing option
  • Cross-device tests
  • Email campaign editor
  • Landing page builder
  • Behavioral tagging

Mailchimp Pricing

The tool’s limited free plan is for 2,000 contacts/month, giving you access to basic features to get you started. Then, pricing starts at $15/month with the Essentials Plan.

Email Subject Line Testers

A great subject line can make the = difference between low and high open rates. To ensure that your subject line isn’t the reason why your campaign lands in the spam folder you can use the following tools:

16. Refine by Moosend – Subject Line Testing

Pricing: Free to use

Best for: Bloggers, Freelancers, SMBs, eCommerce

refine by moosend subject line tester

Refine is Moosend’s free subject line tester tool that you can use on the spot. To access it, you just need to go to the tool, insert your subject line, choose your industry and subscribers, and then hit the “Predict Now!” button.

The AI-powered software will rate your subject line against the industry average and give you suggestions on how to improve its performance.

If your subject line needs optimization, Refine will suggest important changes like adding emojis, personalization, and other elements that will fine-tune your messages.

Best Subject Line Tester Features

  • Ever-advancing algorithm
  • Very easy to use
  • Tailored to each industry
  • Optimization options

Refine Pricing

The tool is available for everyone out there. If you want to step up your email marketing game, though, you can sign up for a free Moosend account and use the tool along with the platform’s powerful A/B Testing features and e-mojo tool for better results.

17. CoSchedule Headline Studio – Subject Line Optimizer

Pricing: Free plan, paid plans start at $19/month

Best for: Bloggers, Freelancers, eCommerce

coschedule headline studio email testing tools

CoShedule’s Headline Studio is a useful email testing tool that everyone can grab to test the performance of their headlines. And since subject lines are pretty much headlines for your email content, you can easily use the software to test them out.

Apart from the standard version, users can benefit from the free browser extension to optimize their headlines on the spot. Also, to make your tests more effective, CoSchedule has a huge data library of 4+ million headlines to help you discover the changes that will really have an impact on your audience.

Best Subject Line Tool Features

  • Advanced headline analysis
  • Headline optimization option
  • Side-by-side copy analysis
  • Headline history access

Headline Studio Pricing

CoSchedule’s Headline Studio comes for free when you register for a free account. To access the premium features, you need to upgrade to a premium plan (through your profile) starting at $19, $59, and $99 per month.

18. Send Check It

Pricing: Free to use

Best for: Freelancers, small businesses

send check it subject line optimizer

Send Check It is a simple yet effective solution to detect problems in your email subject lines. The software is accessible by anyone as long as you have an email address.

When you add your subject line, the tool will automatically analyze it and provide you with information such as your performance score, scannability, reading level, and length.

Moreover, you’ll get useful recommendations on how to improve your subject line, including personalization and punctuation suggestions.

Best Email Testing Tool Features

  • Subject line scoring
  • Spam word detection
  • Sentiment analysis for marketing emails
  • Big subject line database

Send Check It Pricing

Send Check It is another free tool you can use to test your subject lines. To get your results, you only need to fill in your name and email address and there you have it!

Win The Spam War

Email testing tools are essential for every business, big or small!

As we already mentioned above, testing is a crucial part of your marketing strategy, so don’t forget to find the best ones and add them to your marketing toolbox as soon as possible.

If you haven’t already, why not start with Moosend’s design and preview, spam check, A/B Testing, and subject line tester features?

All you need to do is register for a free Moosend account!

Now let the testing begin!

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