The success of your email marketing efforts depends a great deal on your email deliverability. No matter how strong your message is, if it’s not getting into the inbox, you’re wasting your time. In 2025, the world has around 4.6 billion email users. Now, when 45.6% of global emails end up in spam, you see why email deliverability is no easy feat.
We’ll explain what email deliverability testing is, why it matters, and the most important performance benchmarks you should be monitoring to see if your emails are doing all they can for you.
We’ll also show you the best tools and resources at your disposal to run tests and increase your email deliverability. And by the end of this guide, you’ll be an expert at how to read your test results and what you can do to take action to remedy any problems so your emails end up where they’re supposed to, not lost in the internet’s black hole.
What is email deliverability and why does it matter?
Email deliverability: Emails are actually reaching your recipients’ inboxes rather than bouncing or being sent to the spam folder or junk folder.
This isn’t even a question of whether or not your emails were sent. It’s whether or not they’ve been received by the email server, and made it through the spam filters that decide whether your messages are allowed in. If your emails are consistently blocked or filtered as spam, it can damage your sender reputation and hurt your long-term email engagement.
Why is email deliverability so important?
When you email someone, you’d like that email to reach the recipient, wouldn’t you? You didn’t send that email into a void to sit there unread. High deliverability is crucial to the success of your marketing campaigns, as low deliverability can greatly hinder your sales outreach.
Deliverability isn’t only a technical issue. It is closely connected to the success of your campaign:
- Emails that land in spam never get opened, clicked or acted on. In reality, your open rates can be affected by poor deliverability, with less engagement affecting total business results.
- On the other hand, a good email deliverability strategy can increases the odds of your emails hitting the right inbox, delivering your message, getting noticed, and, ultimately, conversions.
Without good delivery testing, you may never even know that your emails are getting marked as spam blocked. That’s why testing and tracking your email campaigns is a must, if you want to hit as many targets as possible and improve performance.
Key email deliverability metrics you should track
To successfully monitor and optimize email deliverability, look out for a number of important metrics that help you understand how your emails are doing.
Inbox placement rate
The inbox placement rate refers to the percentage of emails that get delivered to the recipient’s inbox as opposed to being sent to the spam folder or even being blocked. This is one of the most critical deliverability measures.
Why it matters:
- A low inbox placement rate means your emails are being filtered or rejected by email providers.
- Tracking inbox placement helps you understand how well your email provider trusts your domain and emails.
🔖 Related Reading: Inbox Placement Test: Warmy.io’s Solution to Email Spam Challenges
Bounce rate
Bounce rate refers to the percentage of emails that fail to deliver to the recipient’s inbox. There are two types of bounces:
- Hard bounces: Permanent delivery failures (e.g., invalid email addresses).
- Soft bounces: Temporary issues (e.g., full inbox, server errors).
Why it matters:
- High bounce rates can ruin your sender reputation and lead to a higher likelihood of more emails being tagged as spam or getting blocked.
- Soft bounces are a short-term issue, but frequent hard bounces may suggest a problem with your email list.
🔖 Related Reading: It’s Time to Bounce Back: ESP-Specific Strategies That Actually Work is a report from the Warmy Research Team which takes a deep dive into why emails bounce across different email service providers.
Domain reputation
Your domain’s reputation is a score that ESPs will use to gauge your trustworthiness based on your sending history and your engagement metrics.
Why it matters:
- A high reputation means your emails are more likely to land in the inbox.
- A low domain reputation results in deliverability issues, as ESPs will scrutinize your emails more heavily, possibly filtering them into spam.
- Domain reputation is built over time through consistent sending practices, good list hygiene, and maintaining a positive sending history.
Spam complaints and engagement metrics
Spam complaints occur whens recipients report your emails as spam. A high spam score means your emails are often marked as spam and your emails are unwanted—which can seriously kill your deliverability.
Why it matters:
- It’s also important to monitor engagement metrics such as open rates, click-through rates to understand how well your emails are connecting with your recipients. Low engagement is a signal that your emails may not be as relevant or useful as they need to be.
đź”–Â Relevant Reading: Boost Your Email Click-Through Rate and Skyrocket Engagement
How deliverability testing tools help you
Email deliverability testing tools are a must-have to assure you are in the loop with how your emails are doing and troubleshooting any potential problems before they negatively impact your email campaigns. These tools let you hone your email outreach and build up your sender reputation.
What email deliverability testing tools do
- Analyzes how your emails perform across different email service providers (ESPs), checking whether they land in the inbox, spam folder, or get blocked altogether.Â
- Discover email-related problems in your setup (structure of emails, contents of those emails, and configuration, such as not adding any authentication records) which may be affecting your deliverability.
- Provide insights into your sender reputation, bounce rates, and other key metrics that impact your email success.
How does Warmy’s free email deliverability test work?
Step 1: Access Warmy.io’s Free Deliverability Test
Yes, it’s free! No complicated signups, no technical setup—to test your email deliverability, just head over to Warmy’s Free Email Deliverability Test.
Step 2: Send an email to the provided addresses
Open your email platform (Gmail, Outlook, or your preferred tool) and send a real email to the addresses provided by Warmy. It can be an upcoming campaign or just a test email with links, images, and formatting. This step mimics what your actual recipients would see, and that’s exactly what the tool analyzes.
Step 3: Let Warmy work its magic
In about 3-5 minutes, Warmy will run its analysis and provide insights in a deliverability report:
- The percentage of emails that landed in the inbox, promotions tab, or spam across providers like Gmail, Outlook, and Yahoo.
- The percentage of emails that weren’t delivered at all.
- Whether your domain or IP is listed on any major blacklists.
Step 4: Get clear, actionable results inside the Warmy dashboard
Warmy paid users gain access to even more detailed data from deliverability tests within the platform. And don’t worry—it’s free for seven days during the trial. You can rerun tests and get additional insights, such as:
- Your email deliverability score
- The status of your DNS records
- Spam rate, domain reputation, and IP reputation scores
Best of all, no technical expertise is required. It’s built for marketers, founders, and business owners who want fast, actionable answers without diving into confusing jargon.
Taking the next step after deliverability testing
You now have a clear idea of your current deliverability. Beyond the free email deliverability test, Warmy offers a comprehensive suite of features designed to ensure your emails land in the inbox and perform at their best. Here are some of the standout features:
Check your authentication setup
Proper email authentication is essential for preventing your emails from being flagged or rejected. Just as a passport confirms your identity, email authentication confirms that you’re a trustworthy sender
If SPF, DKIM, or DMARC records are not present or setup is incorrect, email providers will not be able to authenticate the message. They will treat it as potentially unsafe and either block the message or send it directly to the spam folder.
- Configure SPF (Sender Policy Framework): This ensures that only authorized mail servers can send emails on behalf of your domain. Warmy’s Free SPF Record Generator creates a valid SPF record to prevent unauthorized senders.
- Use DKIM (DomainKeys Identified Mail): DKIM adds a digital signature to your emails, confirming their authenticity.
- Implement DMARC (Domain-based Message Authentication, Reporting & Conformance): DMARC helps manage how email providers handle emails that fail SPF or DKIM checks, ensuring that your messages aren’t spoofed. Use Warmy’s Free DMARC Record Generator strengthens security and prevents phishing and spoofing attacks.
Run your cold email content through Warmy’s Template Checker
Even with perfect authentication, your email content can still raise red flags and negatively impact your email deliverability. Warmy’s Template Checker scans your email content for spam triggers that might trigger filters. It provides specific feedback on what needs to be fixed, making it easier to fine-tune your email and re-test until everything is optimized and can avoid spam filters.
Bonus: The Template Checker now has a Chrome Extension, allowing you to analyze your emails in real-time while drafting them, ensuring they’re deliverability-friendly from the start.
Monitor comprehensive data via the Domain Health Hub
Warmy’s Domain Health Hub gives you a comprehensive overview of your domain’s health and performance. You’ll get access to:
- A domain health score based on authentication records, blacklist status, and inbox placement tests.
- Comprehensive DNS status checks to validate your SPF, DKIM, DMARC, rDNS, MX, and A records for stronger security.
- Blacklist monitoring to track if your domain is listed and provide insights for quick fixes.
The Health Hub also tracks your spam rate trends and overall deliverability, allowing you to monitor progress on a weekly or monthly basis.
Implement AI-powered warmup with customizable settings
Warmy.io’s AI-powered email warmup tool gradually builds trust with email providers by mimicking natural email interactions. This feature automatically increases your sending volume over time, so mailbox providers know your emails are trusted and valuable. It also supports over 30 languages to ensure your emails reach global audiences.
The new Warmup Preferences feature is designed to make your email warmup process even smarter by allowing senders to tailor certain preferences, such as:
- Warmup distribution across GSuite, Gmail, M365, Outlook, Yahoo, and even Private SMTP.
- Choosing between engagement patterns of B2B or B2C customers.
Maximize deliverability with advanced seed lists
Unlike traditional warm-up tools that rely on fake email interactions, Warmy.io uses advanced seed lists—genuine email addresses from trusted mailboxes that engage with your emails just like real recipients. This strengthens your sender reputation across multiple email providers.
Additionally, Warmy has introduced an API Endpoint for Established Seed Lists, making it easier to manage and configure your seed list splits directly from your system. What does this mean?
- No more manual updates—automated seed list management saves you time and reduces errors.
- Seamless integration with real-time seed list data that goes directly into your system.
- Better inbox placement—properly configured seed list splits mean fewer bounces and a stronger sender reputation.
Email best practices to improve your deliverability
Here’s a guide to fixing common problems and implementing best practices to maintain strong deliverability over time.
- Review your subject line and content to avoid spammy words or formatting.
- Ensure your email list is clean and up-to-date, removing invalid or inactive addresses that cause bounces.
- Personalize your messages to improve engagement, as low engagement rates can lead to emails being flagged as spam.
- Test your emails using tools like Warmy.io to ensure there are no hidden issues like formatting errors or spam triggers.
- Remove inactive subscribers and those with high bounce rates from your list.
- Segment your list based on engagement levels to send targeted messages to the right audience at the right time.
Take the next step towards deliverability with Warmy
When it comes to getting and keeping strong email deliverability, you need to do more than just hitsend on an email. You need to understand the tech behind email deliverability, adhere to the best practices, and put the right tools in place to monitor and improve your performance.
Warmy is an email deliverability tool that offers everything you need to monitor, test, and improve your email deliverability. From our free email deliverability testing tool to advanced features like AI-powered warmup and domain health tracking, Warmy is here to help you get the most out of your email outreach.
Ready to take control of your email deliverability? Sign up for Warmy today and take the first step toward better deliverability!
