Mail Tester: A Free Tool to Check Your Email Newsletter Against Common SPAM Issues

We’ve been monitoring our email inbox percentages with our partners at 250ok and getting some great results. I wanted to dig in a little deeper to the actual construction of our email and found a great tool called mail tester. Mail tester provides you with a unique email address that you can send your newsletter to and then they provide you an quick analysis of your email against common SPAM checks by junk filters.

The resulting tests are quite robust – the only obvious check missing is whether or not your email is designed responsively to mobile viewports. I don’t believe that impacts an email’s likelihood that it will end up in the SPAM folder, but it will absolutely impact your open and click-through rates.

The output report provides a view of the email with and without images, a text version (not too useful nowadays) and the source. The SpamAssassin filter analyzes your DKIM or DK signature to ensure the source of your email can be validated, verifies the sender IP through a HELO request, and sees whether or not you have a valid SPF record for the email to be sent by your email service. It also verifies the HTML for any errors, validates the percentage of text within the content, tests the images for alternative text tags (useful when email clients block images), and ensures you don’t have javascript, iframes, embedded content or applets within the body. Links are also verified as actually working.

Your sender is also verified against 25 of the most common ipv4 blacklists (BACKSCATTERER, BARRACUDA, BURNT-TECH, CASA-CBLPLUS, IMP-SPAM, INPS_DE, LASHBACK, MAILSPIKE-BL, NIXSPAM, PSBL, RATS-ALL, REDHAWK, SEM-BACKSCATTER, SEM-BLACK, SORBS-DUHL, SORBS-SPAM, SPAMCANNIBAL, SPAMCOP, SPAMHAUS-ZEN, SWINOG, TRUNCATE, UCEPROTECTL1, UCEPROTECTL2, UCEPROTECTL3, and WPBL). Of course, we knew this because 250ok also alerts us with their email blacklist monitoring.

Keep in mind that this is a very rudimentary test and doesn’t take into consideration your list quality, your sender’s reputation, or all of the complex algorithms to do with the terms utilized within your email. Having a deliverability consultant working with you can vastly improve your ability to hit the inbox with each send.

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