17 Email Testing Tools and Tips to Optimize Every Campaign

Testing is critical to email marketing success. Here are some of our favorite email testing tools to help you get started.

The goal of any marketer is to get the right message to the right person at the right time — but to do that, you first have to consider what might go wrong. Some of the biggest issues that affect open and click-through rates can be tested before you hit “send.” Declining to optimize these aspects of your message hurts the chances of your email even making it to your customers.

Consistent testing is crucial for retaining subscribers and increasing engagement. The good news is, with the right email testing tools, you can automate almost everything you need to know. These tools provide comprehensive testing capabilities for marketing teams of any size with any budget. Make them a part of your workflow to improve your email marketing results.

Domain reputation and security tools

Deliverability measures how likely your messages are to make it to customers in the first place. It’s the first thing you should check because none of the other tests matter if people don’t see your emails. A low inbox placement percentage isn’t the end of the world, but it means you have some configurations to check and practices to update.

Your messages may be marked as spam based on their content or due to the reputation of your domain and mail server’s IP address. Your Sender Score, which tells you how likely your emails are to be sent to a spam folder, decreases if spam or phishing messages come from one of your domains. Securing your system and then testing your content against spam filters can decrease the likelihood of deliverability issues.

Our favorite email security and spam score tools are:

• Sender Score from Validity is a free tool that shares the numeric score associated with your IP address. The site also offers a baseline to help you understand the results. A Sender Score above 80 is fantastic; below 70, you’ll want to take steps to repair your reputation.
• dmarcian’s DMARC Record Checker, free, allows you to view and validate your Domain-based Message, Authentication, Reporting, and Conformance (DMARC) record. This protocol prevents spammers from spoofing emails from your domain. While you’re at it, run a free check on your SPF and DKIM records, which are also used by email providers to verify your identity.
• GlockApps DMARC Analytics, from $15/month, provides ongoing DMARC, SPF, and DKIM monitoring. This tool alerts you to suspicious activity, so you can shut it down before any damage is done.
• dmarcian, from $19.99/month, also monitors your DMARC, SPF, and DKIM records continuously and prevents spammers from using your domain. The platform also visualizes data rather than sending you raw XML logs.
• mail-tester newsletter spam test, a free service, generates an email address for you to send your message to. Then it analyzes your content and checks your back-end setup for configuration errors.
• SendForensics Email Deliverability Test, which has a freemium model, analyzes your emails and shares deliverability metrics and benchmarks for your target industry.
• Postmark spam test is a free, browser-based tool. All you do is paste your email into the text box for a free spam score from SpamAssassin. Postmark also offers a JSON API if you want an easy-to-use SpamAssassin setup that can be integrated into your existing tech stack.

Email list verification tools

Verifying your email lists is a must to keep your emails out of spam folders and your email address off blacklists. High bounce rates and low open rates can both tank your sender reputation. Email list decay happens naturally, so email verification and list maintenance is a continual process.

Multiple tools offer this service. Though none are free, they charge one credit to check one address, so the cost is proportional to the size of your email list. We checked the price of 5,000 credits across multiple services to find the best budget-friendly email validation options:

* offers Campaign Monitor integration

Content optimization tools

Your subject line is your first impression, and it may be your only one if it’s not interesting enough to prompt your reader to open the email. Give yourself the best chance of winning a customer over by using subject line testing tools to find the optimal word choice and length.

Likewise, the body content of your email has to be engaging, readable, and accessible if you want to convert customers. While you can use OS-level tools like Apple’s VoiceOver screen reader to check how assistive devices interact with your message, it’s much easier to use the following tools for a comprehensive check (and advice on how to fix any errors):

• Grammarly, free, checks your grammar, spelling, and clarity beyond what Microsoft Word has to offer.
• Hemingway Editor, free, helps you improve readability by marking long or complex sentences, passive voice, and adverbs, among other content writing faux pas.
• Headline Analyzer, a free tool by CoSchedule, scores your subject line based on factors such as word balance, sentiment, and clarity.
• Send Check It Email Subject Line Tester, a free tool, offers a real-time evaluation that looks at aspects such as scannability and grade level. Even more valuable are its previewer, which mocks up your subject line in desktop and mobile views, and language checker, which looks for scammy or otherwise off-putting words.
• Accessible-email.org, free, opens your HTML email in a code editor and points to issues that may decrease accessibility. You can also link the online version of any past email campaign for a full report.

Email preview and functionality testing tools

Optimizing an email for every screen size and client may be the most important thing you do in any email marketing campaign. More than 70% of people delete an email in under three seconds if it doesn’t look right on their device, and 15% go the nuclear route and unsubscribe entirely.

Your campaigns need to work across all operating systems, mobile apps, and desktop browsers. Apple’s iPhone mail app and Gmail currently have the majority of the market share, but you’ll miss a lot of customers if you only optimize your email design for these services. Complete uniformity is impossible when designing for multiple email clients and devices. Focus on usability and consistency instead. If everything looks professional, links are clickable, and the spacing is good, all your customers will have a good email experience.

You can test how emails render by sending to team members who use different devices or email clients, but inbox preview and validation tools offer a more thorough (and efficient) view. Some email services (including Campaign Monitor) have this capability built in. Unfortunately, most standalone services (like Litmus PutsMail and Email on Acid) are pricey. There’s one email testing tool that’s both affordable and has great functionality:

• [email protected], which starts at $20/month, provides everything from email screenshots and HTML validation to a browser add-on. It’s also a pay-as-you-go service, so you can try it out without making a huge commitment.

A roundup of the best email testing tools

In case you missed one, here’s a list of the tools we recommend for email testing and optimization: Domain reputation and security tools

Email list verification tools

Content optimization tools

Email preview and functionality testing tools

Get to the top of your email marketing game

Once you’ve improved your email deliverability and open rates by running the pre-send tests listed above, it’s time for the next round of assessments. You can (and should) use A/B testing to determine which email content and presentation gets the best response from your audience.

The challenge — and the beauty — of email marketing is that you’re never done finding better ways to communicate with your audience. Skipped tests are lost opportunities to improve your engagement and conversion numbers. Don’t bypass the chance to make your next email marketing campaign the best yet. Take a few minutes today to set yourself up with the tools in this post, and you’ll reap the benefits again and again in the future.