Lisa’s App of the Week – Mail-Tester



This App of the Week highlights Mail-Tester, a free tool that lets you test the deliverability of your emails.

By Lisa Heay, Director of Business Operations at Heinz Marketing

For this week’s app of the week post, I wanted to highlight a cool tool I recently learned about – Mail-Tester. Plainly put right on their main page—mail-tester allows you to test the spammyness of your emails. I’m shocked that I’ve spent the majority of my marketing operations career without this tool.

The best part about it is it’s free and simple to use. Created by self-proclaimed geeky email software engineers to solve a need they had to to quickly and efficiently test the quality of their own newsletters, mail-tester was shared with the world to allow users to test the deliverability of their own emails and identify potential issues that could cause them to be marked as spam or rejected by email servers.

To use mail-tester, you simply send a test email to a unique email address provided by the service.


Mail-tester then analyzes the email and generates a score out of 10, with a higher score indicating a better chance of a successful delivery.

You also get a report that provides detailed information on the factors that contributed to the score, highlighting any issues such as spammy content, missing authentication records, suspicious or broken links, incorrect email headers, excessive use of certain keywords, images without alt text, or problems with the email server configuration.

The report also provides recommendations on how to improve the email’s deliverability and reduce its spam score.


One quick tip we’ve discovered—it’s best to add the test address from mail-tester into your database and send a real email to test. It’s an added step, but sample emails from Marketing Automation platforms sometimes aren’t a completely accurate representation of how your email would score.

For example, the subject line may read “[Sample]…”, and in Marketo specifically, the unsubscribe headers aren’t added to test emails. This may be the case with other platforms, as well. You can easily go back to delete those test email records later.

Overall, mail-tester is a useful tool for anyone who wants to improve the effectiveness of their email marketing campaigns or ensure that important emails are delivered successfully. This should be an automatic add to any Marketing Operations professional’s toolbox.

Check out their FAQs for more information, and let me know what you think!

Mail-Tester Fix