20 Best Tools for Testing Emails

Illustration by Pedro Piccinini Illustration of someone multi-tasking.

If you’re sending emails, it’s essential that you test them with email testing tools. No doubt you put a lot of time into writing copy and tweaking your email template. But sending emails without proper testing can leave you open to mistakes, like emails not displaying properly in some email clients, emails landing in spam boxes, and awkward formatting in your email design.

When you neglect to test your email and you experience a #fail, it can be rather embarrassing…

At MailPoet, we want to encourage you to test your email so you can feel confident that you’re sending out the best versions of your newsletters.

There are plenty of useful tools that can help you with testing your reputation, deliverability, rendering of your and even the quality of your subject lines and email content. We use a lot of email testing tools at MailPoet. To help ensure the success of your campaigns, we put together this list of the best email testing tools available.

Tools you’ll find in this list will help you:

  • Test HTML validation,
  • Preview your email design and layout,
  • Check your sender reputation,
  • Improve your deliverability, and
  • Test your email subject lines.

HTML Validation and Email Previewing Tools

MailTrap homepage.

One of the first passes you’ll likely want to make with your email is to make sure that everything is loading properly for each and every email client in a variety of different settings. For example, you want to make sure that your images are loading correctly whether the reader is using Outlook on an iPhone or Gmail on a desktop. Here are some great tools we recommend checking out.

1. Litmus

So, let’s get this one out of the way right off the bat. Litmus is one of the biggest names in email testing, and this tool is used by most enterprise-level operations. Generally speaking, Litmus can help you preview your emails in a wide variety of platforms, and you can change code right in the platform. Litmus is, in fact, so successful that it has acquired other email testing tools, such as PutsMail.

At MailPoet, we use Litmus nearly every week as part of our Quality Assurance step to ensure our email templates look good on every email client, including mobile.  

2. Mailtrap

MailTrap offers a wide variety of email tests you can perform on your email, including preview testing. With MailTrap, you can check your HTML to ensure that it works properly with various email clients. The nice thing about MailTrap is that all of its testing is performed on a fake server, meaning there’s never any chance that you’ll accidentally send out your test emails to your subscribers.

The whole idea behind MailTrap is that you test in a completely safe staging environment, so all of its services are geared towards that idea.

3. Email on Acid

Email on Acid has earned a fairly robust reputation in email testing communities as it has expanded its scope and capabilities. Currently, Email on Acid offers preview testing on 70 different clients on devices. The more configurations you’re able to test your email on, the less likely it is your email will appear broken to any given user.

Email on Acid also puts an emphasis on collaboration, so if you’re working on your newsletter as part of a team, this might be a good option for your small business or group.

4. Preview My Email

Like the other tools on this list so far, Preview My Email is designed to help you double-check your code on various email clients and platforms. The thing that makes Preview My Email stand out is that it gives you multiple ways to test your emails. Currently, Preview my Email allows users to either upload files directly, copy and paste your email content, or send your email to a special Preview My Email inbox.

For an additional cost, you can integrate the Preview My Email API into your workflow (this probably won’t apply all that much to small businesses or community groups, but it’s still good to know).

5. Inbox Inspector

Inbox Inspector lets you preview your emails in more than 25 of the most popular email clients, including popular desktop clients, webmail, and mobile email apps mall in one place. You can try this tool free for 30 days.

6. HTML Email Check

HTML Email Check is a free tool for validating the markup (HTML, XHTML, CSS) of your emails and newsletters. This handy tool also checks images, validates links, and checks for accessibility.

Sender Reputation Testing Tools

mail-tester homepage.

Sender and spam scores are important to test before you send out your emails. The idea is that email clients check for a myriad of variables when they determine whether something is spam (all kinds of algorithms are involved).

These tools will test for red flags that, when added up, might make your email more likely to end up in a subscriber’s spam folder. The best tools examine not only the email you’re sending, but the reputation of where it’s being sent from.

If you’re on WordPress, we have a guide just on diagnosing WordPress sending issues on this Content Management System.

7. Mail-Tester

This easy to use tool created by MailPoet is great for checking your email for spam-related red flags. MailTester will examine your email for SPF and DKIM records (basic anti-spam and anti-fraud protocols), any keywords that might indicate spam to algorithms, and various other metrics.

MailTester will also take a look to see whether or not you are blacklisted by major email clients. All you have to do to get started is send an email to the tester link.

For more on how to use MailTester, check out the MailTester guide in the MailPoet docs.

8. SenderScore

SenderScore focuses mostly on checking your reputation as the sender. All you have to do is type in your domain or your IP address and you’ll get a report on just how trustworthy you are as a sender of emails.

Seeing the full report and analytics does require registration, but this tool is certainly worth it to see if your email sending domain is seen as trustworthy.

9. Postmark

If you don’t want to send your email to a tester link, you can always use the tool called Postmark. With this tool, you simply copy and paste your email code into the tool’s easy-to-use interface. This copy and paste feature makes it easy to check different variations of your email for spam scores. Postmark is a straightforward tool for getting that score and improving your email.

10. Reputation Authority

If you want to know how many “good” emails you’ve sent versus how many “bad” emails you’ve sent, definitely check out Reputation Authority. This tool takes a good look at your domain and processes the type of reputation you’ve earned over the years.

The report that you receive is nice because it can contain historical information as well, so you’ll know whether your domain has always been trustworthy or whether you have a more recent problem.

Bonus tools: Litmus & Email on Acid

Finally, it should be noted that tools such as Litmus and Email on Acid also provide spam and sender reputation checks. This is a common feature among paid email tools, even if it can be found relatively often for free as well.

Deliverability Tools

SendForensics homepage.

If you still need help with your deliverability after testing your sender reputation, you can use this tool to help you identify and fix any deliverability issues you’re having.

11. SendForensics

SendForensics is an email deliverability suite that thoroughly assesses the deliverability of your emails by examining your sender score, the content of your email, loss to spam filters, and other criteria. This tool provides real-time scoring for live campaigns, and compares your deliverability performance with industry benchmarks. You can also set deliverability alerts to monitor your email performance and safeguard your reputation.

Subscriber Verification Tools

EmailListVerify homepage.

When you send an email to an invalid address, you can suffer some real consequences. Those “bounces” (a fancy word for emails that get sent back to you unopened — a kind of digital return-to-sender) can harm your reputation and make your bulk emails look more like spam.

Email verification tools are used primarily to ensure that doesn’t happen, so you know whether an email address on your list is valid before you send out your newsletter. To ensure the safety of your subscribers’ data, we recommend using a paid service to verify your email list.

12. BriteVerify

BriteVerify’s email list verification can help clean your list of duplicates, mistyped domain names and more. I should mention here that BriteVerify if our favorite email verification tool of choice to do this.

Be advised though, list cleaning services will not remove any recent invalid addresses. For good list hygiene, always ensure that any hard bounce emails are removed from your lists!

To use BriteVerify, all you need to do is drag and drop your email list into the app or import directly from your ESP. BriteVerify will then scan and clean your list, and show your total records and cost. When email verification is completed, you can download your clean list, or remove invalid and risky emails from your list.

13. DataValidation

DataValidation guarantees that 99% of your emails will be delivered after using their email list cleaning service. To use this service, you upload or import your email list and then DataValidation starts analyzing your list. When it’s complete, you’ll get a quality report that offers a breakdown of your list’s grades to help you determine when to verify your list.

This tool also provides a comprehensive API for bulk and real-time email verification.

13. Email Checker

Email Checker is relatively simple and straightforward: you just copy and paste an email address into the right field and let the website check to see if that email is valid or not. This option works best if you only have a few emails to check. Premium versions of Email Checker, however, allow you to upload a list of emails that need to be verified. So, if your subscriber lists are substantial, that might be the way to go. Like Email List Verify, Email Checker works on a bulk scale for fees.

14. NeverBounce

NeverBounce will analyze and verify any size email list, providing you with validation results so you can see for yourself how clean your list is. This tool also offers advanced email list cleaning and scrubbing services.

15. QuickEmailVerification

With QuickEmailVerification, you can upload or drag and drop your email list for bulk email verification. Once your email list has been verified, you can either download the list verification report and remove invalid and risky emails from your list.

Subject Line Testing Tools

CoSchedule headline analyzer tool.

Writing the perfect subject line is a challenge. But you don’t have to wait until your email goes out to see if your subject line is working or not. Subject line testing tools can help you evaluate and tweak your subject lines before a single subscriber sees your email.

16. SubjectLine

The SubjectLine tool is a great way to make a check of your subject line both for spam markers and for suggestions to increase your open rate. SubjectLine makes these determinations by looking at data collected from its many partners, so the benefit here is that you’re getting real-time, useful information on which to make some of your subject line-based decisions.

Sometimes the data you receive can be a little shallow, but it’s still a nice tool for evaluating subject lines in a general sense.

17. CoSchedule’s Headline Analyzer

Generally considered to be the single best headline testing tool out there, Headline Analyzer by CoSchedule is a great and handy resource to have in your back pocket. To be sure, a blog headline (of the sort Headline Analyzer was originally developed to test) and a subject line are a bit different, but they both incorporate many of the same features. That’s why Headline Analyzer is a great way to test your subject lines for grammar, structure, and length, among other things.

18. Email Subject Line Grader

Email Subject Line Grader is another great option that was developed specifically to look at email subject lines. Created by Net Atlantic, all you need to do is copy and paste your subject line into the action box and, poof, you get a fair bit of useful feedback. Email Subject Line Grader takes a look at length (which is important, especially on mobile devices) and grammar.

This tool also takes a look at the elements of your email subject line, so if you need a little more or less emotion, you can make appropriate changes.

19. Zurb TestSubject

Over half of all your email subscribers are probably going to first see your emails on a mobile device. You’ve gone to all the trouble to design your email to be mobile compatible; did you remember to check the subject line, too? That’s what TestSubject is for. This tool will show you how your email sender and subject information might look on a mobile device.

Because how that information looks will change from device to device and email client to client. Safari on an iPhone X might look a bit different than Gmail on a Samsung Galaxy, and you want to make sure your subject line looks good on all those devices.

20. Send Check It

Send Check It is a simple yet fairly comprehensive subject line testing tool that looks for scannability, reading grade level, and character and word count. It also assesses the sentiment of your subject line, looks for spammy words, and checks punctuation.

This is a useful tool if you’re not sure why your subject lines aren’t doing so great and need some insight into where you might be going wrong.

For more on how to write subject lines, we’ve got some great posts on the MailPoet blog that can help you out:

Bonus for WordPress users

Since WordPress

What Are Your Favorite Email Testing Tools?

Testing your emails before they go out is a vital step to ensuring that your subscribers are getting the best possible email experience. The more testing you do, the more confidence you can have that your email newsletters are helping your small business or community group grow in the right ways.

There are lots of fantastic email testing tools out there and we’ve tried to cover the best ones here to get you started. Do you have any favorites that we’ve missed? Share your testing tools in the comments below!