If you’ve ever sent a newsletter or cold outreach campaign only to see dismal open rates, chances are your emails never reached the inbox. They may have landed in spam — or worse, been blocked entirely. This is why running an email deliverability test should be a non-negotiable step before hitting “send.”
In this article, we’ll break down what email deliverability really means, why testing is crucial for your campaigns, and how to run tests effectively to boost inbox placement and engagement.
What Is Email Deliverability (and Why It’s Different from Delivery Rate)?
The majority of marketers confuse delivery rate and deliverability. Delivery rate is only to find out whether your email was accepted by the recipient’s server or not. Deliverability, on the other hand, finds out whether that email reached the main inbox or spam/promotions.
This matters because a 99% deliverability campaign can still be doing poorly because the vast majority of those kinds of emails are landing in spam boxes. This is where an email deliverability test becomes useful — it informs you where your emails are being delivered to prior to sending them to your entire list.
Why You Should Test Email Deliverability
Skipping this step is like sending a campaign in the dark. There are three important advantages of consistent testing:
- Prevent Spam Folder Surprises
Testing first lets you catch problems with content, authentication (SPF, DKIM, DMARC), or sending reputation that might harm your inbox delivery.
- Guard Your Domain Reputation
Getting constantly marked as spam decreases your sender rating, subsequently making subsequent campaigns even more challenging to reach. Active testing keeps your domain reputation sound.
- Maximize Open Rates & ROI
Higher inbox placement equates to more views of your message. Directly, that means more opens, more clicks, and more conversions.
What an Email Deliverability Test Includes
A good test is more than sending yourself an email with a test message. A good email deliverability test will generally include:
- Inbox Placement Report – Indicates whether your message is in Primary, Promotions, or Spam in the major ISPs (Gmail, Outlook, Yahoo, etc.).
- Spam Filter Check – Checks your content against leading spam filters to mark questionable phrases or formatting.
- Authentication Check – Checks if SPF, DKIM, and DMARC records are present.
- Blacklist Monitoring – Tests whether your sending IP or domain is listed on major blacklists.
- HTML & Content Analysis – Checks for dead links, incomplete alt tags, and other deliverability-influencing circumstances.
With something like GlockApps Email Deliverability Test, you have all these data in one easy-to-read single report.
Step-by-Step Instructions on Running an Email Deliverability Test
Here is a brief process you can follow:
1. Prepare Your Email Campaign
Construct your email in your marketing automation platform or ESP like you would any normal campaign.
2. Employ a Seed List
Deliverability testing software gives you a proprietary “seed list” of test email addresses on dozens of mailbox providers. Include the list as recipients.
3. Send a Test Campaign
Send the campaign to the seed list before sending it to your entire audience.
4. Check Your Deliverability Report
Verify for inbox placement, spam filter flags, and authentication results.
5. Correct Any Issues
Update your subject line, copy, authentication configuration, or sending domain if needed.
6. Retest if Needed
Re-test continuously until your inbox positioning is where you’d like it to be.
This progressive methodology avoids wasted sends and sub-optimal performance.
Best Practices to Improve Your Test Results
Running tests is just the first step — here’s how to act on the results:
- Authenticate Your Domain: Properly configure SPF, DKIM, and DMARC records.
- Warm Up New Domains & IPs: Gradually ramp up sending volume to build trust.
- Clean Your Email List: Remove inactive subscribers and role-based addresses.
- Avoid Spammy Language: Steer clear of all caps, excessive punctuation, and trigger words.
- Balance Text-to-Image Ratio: Too many images can trigger spam filters.
- Monitor Your Reputation Continuously: Use GlockApps to set up ongoing monitoring.
By following these steps, you’ll consistently hit the inbox and keep your sender reputation healthy.
The ROI of Better Email Deliverability
Consider this: if your list has 10,000 subscribers and 20% of your emails land in spam, that’s 2,000 missed opportunities per campaign. Improving inbox placement even by 10-15% can translate into thousands of extra opens, hundreds of additional clicks, and significantly more revenue — all from the same list and content.
Final Thoughts
Email marketing isn’t just about what you say — it’s about whether anyone sees it. Sending an email deliverability test is a bit like a glance under the hood of your car before a road trip. It ensures that when you click “send,” your campaign actually arrives at the audience you’ve worked so hard to build.
Using GlockApps’ best-in-class testing tools, you’re able to identify problems before they impact your results, safeguard your sender reputation, and ensure better inbox placement each time.