Skip to main content ↓

19 Best Email Testing Tools to Help You Drive Revenue (And Avoid Embarrassment)

Recent stats show email ROI is $36 for every $1 spent. Spoiler alert This isn’t true for everyone, especially those who neglect email testing tools. 

We’ll illustrate. 

Let’s say your marketing team emails 15,000 trial users who may want your product’s annual plan, which costs $504. 

At a 30% open rate, you’ll have 4,500 potential customers. Unfortunately, because your team didn’t test the email, they discovered it didn’t optimally display for your Outlook clients.

If 10% of your trial users use Outlook, that means there’s email rendering issues for 450 people. Factor in a 30% conversion rate and that leaves you with 135 potential lost customers who never clicked your call to action (CTA). Put simply, you lost $68,040 (135 x $504) in potential revenue by not testing your email.

Avoiding unexpected rendering problems is one area where email testing tools shine. When you test your emails, you also prevent issues with grammar and spelling, broken email design, image display, and the dreaded spam trap which hampers email deliverability.

In this post, we’ve put together 19 email testing tools that keep email rendering challenges at bay, help your emails evade spam folders, and ultimately allow you to drive revenue for your business. 

Here are the tools we’ll cover:

Email testing toolType of toolKey featuresPricing
LitmusEmail preview and spam testingPre-send spam testing, integration with 20+ apps, email, phone, and chat support, email preview of 100+ email clients, automated quality assurance and testing of email elements$99-$199 per month for 1-5 full users
MailtrapEmail preview and spam testingSpam testing, access to Mailtrap API, detailed information about email headers, safe email testing with a fake SMTP server, priority supportFree-$299 per month
Email on AcidEmail preview and spam testingUnlimited email previews, spam or deliverability checks, full content checking of links, images, and spelling, commenting access, email and chat support$99-$599 per month for 1-10 users
Preview My EmailEmail preview and spam testingAdvanced HTML editor, unlimited email previews, variable email spam and inbox testing, identification of spam issues$25-$399 per month for 1-10 users
SendForensicsEmail deliverability testingEmail client preview testing, live inbox placement testing, predictive deliverability score, DMARC compliance verification, blacklist and whitelist monitoring, email content analysis and optimization, infrastructure analysis and optimization, ISP reputation analysis$49-$199 per month for 2-10 users
GlockAppsEmail deliverability testingBounce analytics, Email spam tests, DMARC messages, Email template editor, IP reputation monitoring$79-$129 per month for 1-5 users
ZeroBounceEmail address verificationIntegrates with 40+ apps, unknown results are free, 24/7 customer support, IP address geolocation, inbox placement test, blacklist monitoring, 18 validation tools, multiple API keys, email server testPay-as-you-go or $39-$249 per month, 100 free monthly validations
ClearoutEmail address verificationGibberish check for identifying random email addresses, integrates with 100+ apps, duplicate email removal, greylisting verification, blacklist monitoring, spam trap detection, simple APIPay-as-you-go or monthly pricing, 100 free monthly validations
NeverBounceEmail address verificationAPI access, custom list tagging, bulk list email cleaning, automated list cleaning, integrates with 80+ apps, real-time email validationPay-as-you-go or monthly pricing
Lemwarm by LemlistEmail warm-upReal people, no fake accounts, warms up any email domain, 25+ years domain age range, email deliverability booster$25-$29/month
MailReachEmail warm-up12,000+ real inboxes, email reputation monitoring, email monitoring dashboard, live blacklists and DNS checkups, email warm up for multiple email service providers$25 per email account per month for one to five email accounts
FolderlyEmail warm-upAI-based email warmer, email deliverability audit, email placement test, SPF Generator$49 per month
AutoWarmer by QuickMailEmail warm-upTracking of email opens and clicks, automated stop on reply, automated follow-ups, bounce detection, live notifications, A/B testingFree-$79 per month and per inbox
VWOA/B testingVisual editor with HTML attributes and CSS modification support, API access (for enterprise users), report segmentation, multivariate testing, email split testPricing undisclosed, contact sales team
OptimizelyA/B testingAPI access, win rate reporting, email split testing, collaboration within the Optimizely platform, knowledge base, technical, community, and academy supportPricing undisclosed, contact sales team
Mailchimp A/B testingA/B testingA/B testing, multivariate testing, segmentation, integration with 200+ apps, knowledge base, email, live chat, and phone support$13-$1000+/month depending on number of contacts
CoSchedule email subject line analyzerEmail subject line testingPreview of subject line on desktop and mobile, analysis of words that can increase/decrease opens, subject line scoreFree
Email Subject Line GraderEmail subject line testingProvides recommendations to fix technical problems with subject line, scannability, length, readability, subject line sentiment, identifying spam words, and moreFree
Send Check ItEmail subject line testingProvides recommendations to fix technical problems with subject line, scannability, length, readability, subject line sentiment, identifying spam words, and moreFree

Email preview and spam testing tools

With over 300,000 potential renderings for any given email, there’s a wide range of differences in how a message can appear on different email clients. The same applies to email on desktop and mobile devices. This is where email preview tools work their magic. 

Luckily, you can also use these tools for spam tests and ensure your email lands in your recipient’s inbox. Here are some excellent email preview and spam testing tools worth checking out:

1. Litmus 

Litmus is one of the best email testing tools used by small to enterprise-level organizations.

With Litmus, you can preview your email’s appearance on 100+ popular email clients like Outlook, Apple Mail, Gmail App, Samsung Mail, etc. And with the Litmus Spam Testing feature, you can evaluate your email against spam filters and receive notifications if your email is blocklisted or if you incorrectly set up your DMARC record.

Email features of Litmus

  • Pre-send spam testing
  • Integrates with 20+ apps
  • Email, phone, and chat support
  • Email preview of 100+ email clients
  • Automated quality assurance and testing of email elements like broken links, alt text and loading speed

Litmus pricing

  • Seven-day free trial
  • Basic plan: $99 for 1,000 email previews every month for one full user
  • Plus plan: $199 for 2,000 email previews every month for up to five full users
  • Enterprise plan is available at a custom price

2. Mailtrap

Mailtrap’s email preview works by analyzing your HTML and CSS and listing all issues it finds. Unlike Litmus, you can’t generate a preview for each email client, but you can identify common red flags among popular clients like Gmail and Outlook.

Besides Mailtrap’s preview and spam testing functionalities, an excellent feature is the ability to conduct all email tests on a fake server, meaning the probability of unintentionally sending test emails to your email subscribers is zero.

Email features of Mailtrap

  • Spam testing
  • Access to Mailtrap API
  • Detailed information about email headers
  • Safe email testing with a fake SMTP server
  • Priority support on all plans except the free plan

Mailtrap pricing

  • Access to a free plan
  • Five other pricing options, ranging from $9 for the individual plan to $299 for the enterprise plan every month

3. Email on Acid

Email on Acid is a top email testing tool used by marketers, developers, and enterprise companies like Toyota, The New York Times, and IBM. With Email on Acid, you can preview your email’s appearance on 90+ email clients and devices.

Plus, Email on Acid tests your message against 23 popular spam filters. The outcome? You gain insights on deliverability issues and fix them before pressing your send button.

Features of Email on Acid

  • Unlimited email previews
  • Spam or deliverability checks
  • Full content checking of links, images, and spelling
  • Commenting access on email previews for team collaboration
  • Email and chat support. Dedicated account rep on all plans, except The Basics plan

Email on Acid pricing

  • Seven-day free trial
  • The Basics plan: $99 per month for one user
  • Premium plan: $179 per month for three users
  • Professional plan: $599 per month for 10 users
  • Enterprise plan is available at a custom price

4. Preview My Email

Designers, marketers, and developers use Preview My Email to assess their email appearance on over 54 clients. Preview My Email allows you to test emails by uploading your saved HTML code, copy-pasting your email, sending your email to a special Preview My Email inbox, or submitting your email via an API. 

With Preview My Email, you can identify and fix spam issues as this tool checks your original IP against over 50 of the most common industry blacklists.

Features of Preview My Email

  • Advanced HTML editor
  • Unlimited email previews
  • Variable email spam and inbox testing depending on your plan

Pricing of Preview My Email 

  • Seven-day free trial
  • Standard plan: $25 per month for one user
  • Business plan: $45 per month for one user
  • Professional plan: $160 per month for 10 users
  • Enterprise plan: $399 per month for 10 users

Email testing tools for deliverability

Writing great marketing emails that get opened, read, and acted on is one thing; ensuring the deliverability of the email is another. Before checking out the email deliverability tools, here’s a quick video on what you can do to make email delivery seamless. 

5. SendForensics

SendForensics is an advanced email deliverability suite that uses multiple AI insights to gauge an email’s ability to reach your recipient’s inbox. This tool measures your email’s quality by evaluating it against global filtering-systems/ISPs, including human recipients.

Adding SendForensics to your email toolbox allows you to monitor your sending infrastructure, email content (including links), IPs, domains, and other things that can impact deliverability. As a bonus, this testing tool has email preview functionality.

Features of SendForensics

  • Email client preview testing
  • Live inbox placement testing
  • Predictive deliverability score
  • DMARC compliance verification
  • Blacklist and whitelist monitoring
  • Email content analysis and optimisation
  • Infrastructure analysis and optimisation
  • ISP (Internet Service Provider) reputation analysis
  • AI-driven insights of email content, sending infrastructure, and reputation

SendForensics pricing

  • 14-day free trial
  • Brand plan: $49 per month for two users
  • Company plan: $79 per month for five users
  • Agency plan: $199 per month for 10 users

6. GlockApps

GlockApps is a comprehensive email deliverability solution that provides inbox insights, DMARC analytics, bounce tracker, IP reputation monitoring, and free spam testing. 

Using GlockApps gives you access to uptime monitoring of your IP, website, SPF, DKIM, and DMARC records. Monitoring these helps secure your email reputation, maintain email health, and improve website conversions. On top of these, the free spam checker allows you to track your email’s destination (inbox, promotion, and spam folders) after you hit send. With this, you fix all deliverability challenges so you have an optimum conversion rate.

GlockApps features 

  • Bounce analytics
  • Email spam tests
  • DMARC messages
  • Email template editor 
  • IP reputation monitoring

GlockApps pricing

  • Access to a free account
  • Basic plan: $79 per month for one user
  • Business plan: $129 per month for five users
  • You can also create a custom plan

Email testing tools for verifying invalid addresses

Sending emails to invalid‌ addresses causes them to bounce back unopened. One reason for email bounce is invalid email addresses; and with increased bounce frequency comes increased hits to your reputation, making your future bulk emails appear like spam. 

With these tools for verifying email addresses, you can permanently clean your list and nip this challenge in the bud.

7. ZeroBounce

ZeroBounce is one of the popular email verification tools that can validate your email list with a high-level of accuracy. Whether you want to clean a list of 100, 1,000, or 10,000 subscribers, this tool takes from seconds to some minutes to purge your list of invalid email addresses.

Besides email verification, ZeroBounce has intuitive email validation APIs that automate and assess the quality of your contacts at the point of capture. Also, ZeroBounce has functionalities for email deliverability tests and real-time blacklist monitoring.

ZeroBounce features

  • Integrates with 40+ apps
  • Unknown results are free
  • 24/7 customer support
  • IP address geolocation
  • Inbox placement test
  • Blacklist monitoring
  • 18 validation tools
  • Multiple API keys
  • Email server test

ZeroBounce pricing

  • ZeroBounce operates pay-as-you-go and monthly pricing models. For instance, the cost of validating 2,000 emails is $15 monthly or $16 on pay-as-you-go. You also have access to 100 free monthly validations.

8. Clearout

Clearout is a great email verification tool with similar features like ZeroBounce. Like ZeroBounce, this tool stands out because it validates a subscriber’s email from the point of capture. 

So whether you intend to capture emails via your website, exit pop-ups, woocommerce checkouts, surveys/polls, chatbots, and newsletters, with Clearout, you can verify emails before they make it to your list. This prunes your list of invalid subscribers from the get-go, limits the chances of hard bounces, and ‌improves deliverability. 

Also, Clearout cleans your list of email duplicates, has spam detection algorithms, and verifies if your recipient’s mailbox can accept new emails. 

Clearout features

  • Gibberish check for identifying random email addresses
  • Integrates with 100+ apps
  • Duplicate email removal
  • Greylisting verification
  • Blacklist monitoring
  • Spam trap detection
  • Simple API

Clearout pricing

  • Like ZeroBounce, Clearout operates pay-as-you-go and monthly pricing models. For instance, the cost of validating 5,000 emails is $31.50 monthly or $35 on pay-as-you-go. You also have access to 100 free monthly validations.

9. NeverBounce

NeverBounce is another excellent email verification tool with features similar to Clearout.

This tool provides real-time email verification, and it analyzes and verifies small to large lists. The best part? You can automate list cleaning by connecting your email provider to NeverBounce, meaning your email list will always be accurate and you’ll have peak deliverability.

Features of NeverBounce

  • API access
  • Custom list tagging
  • Bulk list email cleaning
  • Automated list cleaning
  • Integrates with 80+ apps
  • Real-time email validation

NeverBounce pricing

  • NeverBounce operates pay-as-you-go and monthly pricing models. Let’s say you have 5,000 emails to validate. That’ll cost $49 monthly or $40 on pay-as-you-go. You also have access to a free trial.

Email warm-up tools for improved deliverability

If you have a new email or one you haven’t used in a while, warm it. 

Warming your email helps you establish a reputation for your IP and this prevents your email from landing in spam folders. While you can warm emails manually, an effective way to achieve similar results in less time is by using email warm-up tools. Here are some of them:

10. Lemwarm by Lemlist 

Lemwarm is one of the best email warm up tools that helps you wave goodbye to spam folders. 

The tool operates by progressively sending and engaging with small amounts of personalized emails, depending on your email domain’s age. Best part? Rather than send and respond to emails using fake accounts, Lemwarm exchanges emails with its  20,000+ people from over 100 countries. The result? Your sender reputation is high and your emails reach your recipients’ primary inboxes. 

Features of Lemwarm

  • Real people, no fake accounts
  • Warms up any email domain
  • 25+ years domain age range
  • Email deliverability booster

Lemwarm pricing

  • Lemwarm pricing is $29 per month when billed monthly and $25 per month when billed yearly

10. MailReach

This intelligent email warm up tool is great for incrementally sending and engaging with emails and placing those that land in spam and promotion folders in the primary inbox. Besides that, MailReach exchanges emails with multiple email service providers, keeping your reputation high with Gmail, Outlook, etc.

Plus, its intuitive dashboard gives insights on your warm up status, allowing you to know where emails from your campaigns will end up.

MailReach features 

  • 12,000+ real inboxes
  • Email reputation monitoring
  • Email monitoring dashboard
  • Live blacklists and DNS check ups
  • Email warm up for multiple email service providers

MailReach pricing

  • Starter plan: $25 per email account per month for one to five email accounts
  • Scale plan: Starts at $19.50 per email account per month for over six email accounts. The pricing reduces with more email accounts to warm.

Powerful email marketing, minus the headaches

Nutshell Campaigns plugs directly into your CRM data, so you can create highly targeted audience segments, track the impact of your emails in real-time, and manage all your communications out of a single tool. Get started for free!


an envelope with a piece of paper in it that says to audience

12. Folderly

As a popular AI-based email warmer, Folderly identifies, solves, and maintains all issues related to email deliverability. With Folderly, you can easily set up, track, and monitor your email warm up progress.

Furthermore, Folderly provides other email marketing solutions like email deliverability audit, email placement test, and it has an SPF Generator.

Folderly features 

  • Automatically generated senders
  • GPT-3 powered interactions
  • Email warm up dashboard
  • Integrates with 10 apps
  • Email placement test

Folderly pricing

  • Folderly has a single pricing for its email warm up feature and that’s $49 per month

13. AutoWarmer by QuickMail

AutoWarmer is another powerful email warming tool like the others on this list. 

One of its perks is the availability of a free-forever plan. While the free plan is great if you’re on a budget, it also limits your access to only warming inboxes on Gmail/Outlook/SMTP. You’d need to upgrade to a paid plan to use functionalities like the warm up deliverability report. 

AutoWarmer features 

  • Tracking of email opens and clicks
  • Automated stop on reply
  • Automated follow-ups
  • Bounce detection
  • Live notifications
  • A/B testing

AutoWarmer pricing

  • AutoWarmer Plan: Free
  • Starter Plan: $59 per month and per inbox for sending 500 emails per day. An extra inbox cost $35 per month.
  • Pro plan: $79 per month and per inbox for sending 1,500 emails per day. An extra inbox cost $45 per month.

A/B testing tools

Conducting A/B tests is an excellent way to assess the effectiveness of email elements like your subject line, body copy, personalization, CTA, and more. 

A/B tests work by first deciding on one specific element to test, the number of versions to test, and your sample size. Done right, these A/B testing tools won’t only increase your open rate, but increase your conversions.

14. VWO

VWO is a popular A/B testing tool that global brands use to test not just emails, but also web pages, apps and products. This tool can A/B test any element of your email campaign and measure the performance of the best variant. 

Although this tool has multivariate testing functionality for evaluating multiple elements at once, it’s an email marketing best practice to test one element at a time. 

VWO features

  • Visual editor with HTML attributes and CSS modification support
  • API access (for enterprise users)
  • Integrates with 40+ apps
  • Report segmentation
  • Multivariate testing
  • Email split test

VWO pricing

  • VWO pricing is undisclosed. You’ll have to contact their sales team if their Growth, Pro, or Enterprise plan interests you

15. Optimizely

Optimizely is another excellent A/B testing tool for testing elements of your email. Like VWO, Optimizely does multivariate analysis and has a suite of digital experience tools for ecommerce, websites, content management, and marketing planning.

Features of Optimizely

  • API access
  • Win rate reporting
  • Email split testing
  • Integrates with 180+ apps
  • Collaboration within the Optimizely platform
  • Knowledge base, technical, community, and academy support

Optimizely pricing

  • Optimizely pricing is undisclosed. You’ll have to contact their sales team if their Grow, Accelerate, or Scale plan interest you.

16. Mailchimp A/B testing software

Mailchimp is a well-known email marketing tool with A/B testing functionality. With Mailchimp, you can select the list segment for your campaign, pick the variable you want to test, set the percentage of recipients for the test, and determine the parameter for the winning variant.

Premium users also have access to multivariate testing for three variables and up to eight combinations. 

Mailchimp features 

  • A/B testing
  • Multivariate testing
  • Advanced segmentation
  • Integrates with 200+ apps
  • Knowledge base, email, live chat, and phone support

Mailchimp pricing

  • Email testing access is unavailable in the free plan
  • Essentials plan: $13-$350 per month depending on number of contacts for three users without multivariate testing access
  • Standard plan: $20-$700 per month depending on number of contacts for five users without multivariate testing access
  • Premium plan: $350-$1500 depending on number of contacts per month for unlimited users with multivariate testing access

Email subject line testing tools

An excellent subject line attracts a click, a weak subject line could get ignored, and an email recipient could trash a spammy subject line immediately. So as the first thing your subscribers see, it’s vital to evaluate your email subject line before hitting send. These tools help. 

17. CoSchedule email subject line analyzer

This is one of the best tools for assessing the quality of your email subject lines. Having this tool in your email arsenal allows you to gain insights on what can increase your open rate. 

With CoSchedule email subject line tester, you’ll see the previews of your subject line on desktop and mobile, words that can increase and decrease opens, and a subject line score. The best part? This email subject line analyzer is a free tool. 

18. Email Subject Line Grader

Email Subject Line Grader is another free tool for evaluating subject lines. Like CoSchedule, this tool assigns a subject line score after assessing the word and character count, including word mixture and balance of your subject line.

19. Send Check It

Send Check It is a free email testing tool that ensures your subject line hits the mark. 

After assessing your subject line, Send Check It provides recommendations on what to fix. These include technical problems with your subject line, scannability, length, readability, subject line sentiment, identifying spam words, and more..

Send smarter with Nutshell

After warming your email, testing your subject line, running A/B tests and whatnot, you’ll need a centralized location to send, track, and measure the results of your campaign. 

👉Enter Nutshell. Nutshell CRM software integrates your marketing and sales data in one unified platform. This prevents you from juggling multiple software dashboards by providing the reports and communication tools you need in a single view.

Plus, Nutshell integrates with 45+ business apps, has email preview functionality through Nutshell Campaigns, allows you to test different versions of your email, and we don’t deliver bounced emails, meaning your deliverability remains intact and you maintain optimum email ROI. 

In a nutshell, you should give Nutshell a shot 🤩. 

Best part? You can try Nutshell free for 14 days.


Want to kick the tires a bit?

No problem. To see if Nutshell is the right choice for your sales team, start a 14-day free trial today!


an illustration of a person in a green shirt standing in front of a group of people in the shadows
Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.

Join 30,000+ other sales and marketing professionals. Subscribe to our Sell to Win newsletter!