How to Test Email Deliverability

Testing email deliverability is an essential step in your marketing efforts. It should be done before you send your next campaign so that your emails are delivered to the correct email inboxes and your marketing effort doesn’t go to waste.

What Is Email Deliverability?

Before we explain how to test email address deliverability, it’s essential to know what the term means because there’s a lot of confusion surrounding it.

To start with, there’s a difference between “deliverability” and “delivery.” While the latter is used to describe whether a recipient’s server accepted a marketing message, the former is a marketing term used to distinguish emails that have made it to the inbox from those that haven’t.

Technical issues, such as an unstable connection or server overload, are responsible for most email delivery issues. The good news is that email delivery tests are usually unnecessary because mail servers automatically report delivery errors. On the other hand, problems with email deliverability stem from a poor sender reputation score, bad content quality, and unclean mailing lists containing incorrect addresses, among other things.

Although it takes time to learn how to improve email deliverability, performing an email deliverability test is a quick process that takes only a few minutes from start to finish.

Factors That Affect Deliverability

Most marketers feel that they have achieved a perfect email deliverability rate when 95% or more of the emails they send are delivered to the intended inbox. There are several factors that can prevent mailings from reaching your audience. Here are the main factors that affect the success of your marketing campaigns:

When to Test Email Deliverability?

According to data published by EmailToolTester, the average deliverability rate hovers around 80%. As such, anything above this number is considered a good email deliverability rate. Anything lower than 80% should prompt an email deliverability test.

Additionally, it’s always a good idea to perform testing before the start of any email marketing campaign to maximize its effectiveness. If the campaign has a longer duration, consider testing email deliverability at regular intervals.

There are several ways to check email deliverability, and the best testing tools available combine these tests into a single straightforward process:

Top Email Deliverability Testing Tools

The good news is that marketers don’t have to worry about too much the technical side of things since testing email deliverability is quick and easy using the following tools. These services don’t offer bulk email verification. Instead, you’ll send one of your campaign emails to a specified address, and the service will provide you with information such as your spam score and whether your campaign’s email address is on a block list.


Developed by email software engineers to be cheap, simple, and efficient, is a no-frills tool that lets you test email deliverability in one straightforward step. All you need to do to obtain an accurate deliverability score is send a message to the provided address.

This is one of the best email address tester apps that will tell you what SpamAssassin, a spam checker developed by the Apache Software Foundation, thinks about your message. You will also learn if your mail account is on a block list or not fully authenticated, among other things.

With the free version of, you can perform up to 3 tests per day, which should be enough to learn how the tool works.

👍🏼   Pros:
  • Provides a JSON API for paid plans
  • Customer service provides an excellent response time
👎🏼   Cons:
  • Results are deleted after seven days with a free account
  • Only checks for a spam score with a free account

2. MxToolbox

MxToolbox is a well-known name when it comes to email testing and monitoring, and its tool analyzes the headers, the blocklist reputation of your outbound IP address, and your SPF records. It then generates a comprehensive deliverability report, providing you with a wealth of useful information that you can closely analyze and use to improve the performance of your marketing campaigns.

Free users are limited to one free monitor with access to the top 30 blocklists, so consider upgrading to the paid plan if you’re interested in access to multiple monitors and more blocklists.

👍🏼   Pros:
  • Dashboards are handy
  • Features include campaign management and event-triggered actions
👎🏼   Cons:
  • Can be expensive for marketers with several domains

3. Spam Check by Postmark

Spam Check by Postmark is an easy-to-use online tool that lets you instantly check the SpamAssassin spam score of your messages. SpamAssassin is an open-source spam checker that uses a variety of spam-detection techniques to separate spam from legitimate emails.

It’s used by many service providers, so knowing how it sees your messages is beneficial in determining their deliverability. What’s great about Spam Check by Postmark is the fact that you can simply paste a message including its full headers and content—no need to send it anywhere.

👍🏼   Pros:
  • Free API service
  • Fully functional scoring and reporting tool; no need to write code
👎🏼   Cons:
  • API may be updated, removed, or changed at any time

4. GlockApps

GlockApps is a full-featured service that offers everything you’ll need to maximize inbox deliverability from an email deliverability tester to a blocklist monitor, spoofing detector, HTML error checker, and more.

These tools perform virtually all checks marketers use, including sending your IP and domain information against more than 50 industry blocklists and tracking if your content or IP is blocked by Gmail, Yahoo, or other ISPs. All MailChimp users will appreciate that GlockApps can easily test their marketing campaigns directly from its website, thanks to the integration between the two services.

Free users get three detailed reports, and they can then choose between annual, monthly, or on a per-test basis plans.

👍🏼   Pros:
  • Easy to use and consistent
  • Provides detailed reports and suggestions to improve deliverability
👎🏼   Cons:
  • Difficult to test double opt-in confirmation emails
  • API is poorly documented

5. SendForensics

If you’re interested in generating detailed deliverability reports, check out SendForensics. This tried-and-tested email deliverability checker highlights the issues that send your emails to the spam folder by performing pre-emptive email deliverability testing and real-time scoring for live sends.

You can compare your rate with industry and regional benchmarks to know how well you’re doing and set alerts to quickly discover emerging issues before they become huge problems that can potentially ruin your marketing campaign.

👍🏼   Pros:
  • Free account for a single user and a single sending domain
  • Offers pre-send optimization and post-send measurement
👎🏼   Cons:
  • Recommendations are sometimes contradictory and vague

Why You Should Care About Email Deliverability

Email is gaining in popularity, and more people prefer to use email to communicate with businesses. Email is their preferred choice over social media, text messaging, and direct mail. Even though it has become the primary means of communication for many people, you can’t always be assured that an email address you added to your marketing list a few months ago will be delivered. People change addresses or may delete those email accounts completely. The result being that messages aren’t delivered or are delivered to the wrong inbox.

A successful marketing campaign depends on deliverability; messages must reach the inbox of the intended recipients, and those people must be compelled to read those messages. Why is deliverability important? The highest return on investment that organizations see comes from their email marketing efforts. So, the more people that read those campaign mailings means that more people will respond to the marketer’s call to action. Which, in turn, results in a higher sales rate.


Spam accounts for most of all email traffic, so it makes perfect sense for service providers to aggressively protect their users from unwanted messages. Unfortunately, no spam protection is perfect, so it’s not uncommon for legitimate emails to end up in the spam folder. To ensure that your marketing effort doesn’t go to waste, you need to check email address deliverability from time to time using the tools listed in this article.

Looking for how to validate email addresses for free? Check out our top of the best free email verification services.

How to Test Email Deliverability – FAQs

How do you test email deliverability?

It can be easily tested using one of the many available email deliverability tools, most of which can be used for free with certain limitations.

How do you know if an email is delivered?

Unless either your mail server or the recipient’s mail server generates an error message, then the message has most likely been delivered—no need to perform an email delivery test.

How do I check email deliverability in Salesforce?

Emails sent through Salesforce originate from one of several possible Salesforce IP addresses, which may be blocked by the recipient. To check email deliverability in Salesforce, follow these instructions.

How can I test an email without sending it?

Some tools let you test the content of your message against spam filters without sending it. You can also test the configuration of your mail server to verify that it’s behaving the way it’s supposed to behave.

What affects email deliverability?

The likelihood that your campaign emails reach your intended audience depends on several factors. Email deliverability depends on a combination of your sender reputation, your ability to avoid spam traps, having the correct address for your recipients, and the engagement level of your messages.

How does email deliverability work?

Email deliverability depends on a message reaching the intended inbox. Marketers must take extra measures to make sure the addresses on their mailing lists are real, accurate, and valid. Most marketers use a verification service to check their lists.