Some argue that the benefits of email marketing are overrated, but data shows that it works, as proven by these figures:

  • Currently, there are 4.26 billion email users worldwide, and this number is set to grow to 4.73 billion users in 2026.
  • Nearly 90% of professionals, regardless of industry, prioritize email over any other communication means.

But no matter how great your marketing campaign is or how well-crafted your messages are, you cannot reap email marketing benefits fully without maintaining a clutter-free distribution list—one of the primary uses of email verification services. But what is email verification, exactly?

What Is Email Verification?

Email verification simply refers to the process of ensuring that an email address has a corresponding inbox. That guarantees it will receive any email sent to it. If you’re a digital marketer, that translates to getting your message across, which would hopefully result in lead generation at the very least or conversion at most. The more sales conversions, after all, the greater the revenue.

How Does Email Verification Work?

Email verification services typically employ several checks to ensure the validity of any email address, which include the following:

  • Format check: The Internet Engineering Task Force (IETF) has established standards that every email address must follow. IETF, for instance, requires that each email address have a local-part (usually a person’s or department’s name), the @ sign, and the domain as in name@company[.]com. Any email address that does not conform to these standards is usually deemed invalid by the best email verifiers. This check uses a syntactic email validation engine that determines if an email address follows IETF specifications.
  • Simple Mail Transfer Protocol (SMTP) check: Any email address that cannot receive messages is undoubtedly invalid. It should have a corresponding SMTP server to do that. The best email verification services check for mailbox existence by emulating email sending to check for an SMTP connection.
  • Domain Name System (DNS) and mail exchange (MX) record check: Any domain (including email domains) needs a corresponding DNS server to direct users to the correct pages (or, in this case, mailboxes). Determining if an email address, therefore, has appropriately configured DNS records (specifically MX records) and a corresponding DNS server (MX server in this case) is a crucial step in email validation. Any email address without a corresponding MX server and adequately configured MX records cannot receive messages.
  • Free check: Many if not all signup pages require users to key in their corporate instead of personal email addresses since these are more useful for lead generation in business-to-business (B2B) scenarios. The best email verifiers can check if any given email address is provided by free services like Gmail or Yahoo!
  • Disposable check: While not all disposable email address users are malicious (some may just take their privacy more seriously than others), some, unfortunately, are freemium abusers. The best email verification services can instantly tell users if an email address is from disposable or temporary email services like GuerillaMail, Mailinator, or 10 Minute Mail.
  • Catch-all check: Catch-all addresses are those that accept all emails that are sent to a domain name. Companies typically use catch-all email addresses for general inquiries that users may not know who exactly in the organizations should receive. Examples of these include info@company[.]com, inquiry@company[.]com, or support@company[.]com. These are not invalid email addresses, though. Their owners are just undefined, but for marketing purposes, they may not be ideal contact means.

Use Cases of Email Verification Services 

While the best email verifiers are most beneficial for digital marketers, they can also help cybersecurity and brand protection specialists and software-as-a-service (SaaS) and website managers with their jobs. The sections below show how.

Clean Up Distribution Lists

Digital marketers can use the tools to eliminate email addresses that are not likely to help them generate leads or convert contacts into paying customers from their distribution lists. Those email addresses include disposable and catch-all addresses. Email validation can thus aid them in driving down their bounce rates, making it less likely for them to end up on any blocklist.

Keep Disposable Email Addresses Out

Email validation can also be a healthy practice for cybersecurity pros who wish to keep threat actors who may be hiding behind erroneous or disposable email addresses out of their networks.

Maintain a Healthy Domain Reputation 

Brand protection agents can also make it a habit to verify email addresses to keep their domain reputability intact. Getting flagged as a spammer as a result of suboptimal email verification practices can severely damage your reputation.

Avoid Freemium Abuse

Website owners and SaaS providers, meanwhile, can reduce faulty signups that can adversely affect their B2B lead generation with the help of the best email verification services. They can keep freemium abusers from exploiting their freemium offerings by disallowing invalid email address usage from registration pages.

Criteria for Choosing the Best Email Verification Services

When choosing the best email verifiers, opt for the one that conducts the most number of checks on email addresses. That way, you can avoid dealing with as many faulty email users as possible. Here’s a brief comparison of the checks done by the best email verification services featured in this post.

Checks DoneWhoisXML APIQuickEmailVerificationTrueMailEmail Verifier APIMailerCheckEmail ValidatorMailgunSendGrid
Format check
SMTP check
DNS and MX record check
Free check
Disposable check
Catch-all check

Knowing if their available output formats are compatible with your systems and applications may help as well. Finally, checking out their prices and which fits your budget and requirements best is also advisable.

Email Verification Services You Can Choose From

We compared eight of the best email verification services available in the market today to help you get started on your journey toward better email marketing, cybersecurity, brand protection, and freemium abuse prevention.

Below is the list of the best email verification services we will cover in this post.

  1. WhoisXML API Email Verification Tools
  2. QuickEmailVerification
  3. TrueMail
  4. Email Verifier API
  5. MailerCheck
  6. Email Validator
  7. Mailgun
  8. SendGrid

WhoisXML API Email Verification Tools

WhoisXML API provides several email verification tools to choose from, including a web-based lookup service, an application programming interface (API), a bulk email verification tool, and disposable email domain data feeds. All these can reduce a company’s chances of dealing with temporary, fake, or even harmful email addresses.

WhoisXML API Email Verification Tools Homepage

You can access Email Verification Lookup through any browser. And all users need to do is type the email address they wish to validate into the input field and hit “Lookup.”

WhoisXML API Email Verification Lookup

The results of each check come in an easy-to-read format. Each report also comes with a custom Uniform Resource Locator (URL) or link at the bottom that you can share with your colleagues. You can also download the report in JavaScript Object Notation (JSON) format, which any text editor can read. It looks like this:

WhoisXML API JSON report

Email Verification API, meanwhile, gives the same results as the web-based lookup tool but has the added benefit of being integrable into your existing systems. It provides results in JSON or eXtensible Markup Language (XML) format.


Both Email Verification Lookup and Email Verification API are suitable for querying small email address volumes or one-by-one checks. But if you need to validate thousands of email addresses, a bulk verifier may be more apt. WhoisXML API offers Email Verification Bulk API and Email Verification Bulk Lookup as possible solutions. These tools function the same way the first two products above do but can process as many as 50,000 email addresses per query. Their results also come in comma-separated values (CSV), JSON, or XML formats.

Checks done by these products include format check, SMTP check, DNS and MX record check, free check, disposable check, and catch-all check.

Additionally, users in need of better protection from potential abusers and fraudsters can also benefit from monitoring disposable email domains to keep as many of these out of their networks. Disposable Email Domains Data Feed provides comprehensive and regularly updated lists of disposable email domains in text format. You can include these in your blocklist for utmost protection.

WhoisXML API Disposable Email Domains

WhoisXML API offers free plans and charges less than US$1 for 1,000 email verification queries.


QuickEmailVerification specifically targets business users that want to grow their customer bases. Like the first vendor on our list, this provider has an API and a bulk verification tool. These products can be helpful for sales and marketing teams when checking the accuracy of email addresses to improve conversion rates, reduce email bounces, and avoid fake email addresses that will not produce returns on investment (RoIs). The tools provide results in JSON format.

Checks done by QuickEmailVerification tools include format check, SMTP check, DNS and MX record check, free and disposable check, as well as catch-all check.

QuickEmailVerification has a free plan and charges less than US$1 for 1,000 queries.

QuickEmailVerification Homepage


TrueMail claims to rid clean mailing lists and increase clients’ deliverability rates up to 99%. Like the first two featured vendors, its product is integrable into existing systems and solutions. Unlike them, however, TrueMail does not have a bulk email verifier offering. The results also downloadable in the form of JavaScript Object Notation with Padding (JSONP) files, as well as in XML and JSON formats.

Checks include format check, free check, disposable and catch-all checks.

Interested users can avail of TrueMail’s free plan or pay less than US$2 per 1,000 queries.

TrueMail Homepage

Email Verifier API

Email Verifier API provides an enterprise-grade cloud-based transactional email verification solution that is compatible with all programming languages. According to its website, the product helps users avoid bounces, spam traps, honeypots, and more that could negatively affect their email deliverability. The provider does not have a bulk verifier offering nor a web-based tool. The results are available in XML and JSON formats. 

Checks done by Email Verifier API include format check, free check, disposable check, and catch-all check.

Unlike the three previously mentioned services, Email Verifier API only offers the first 100 queries free of charge. On average, every 1,000 queries made on the API would cost users US$2.

 Email Verifier API Homepage


MailerCheck is an all-in-one tool designed to improve email deliverability, with a guaranteed 98%+ delivery rate. It offers single and bulk email verification, advanced real-time API verification which is able to run on multiple applications, and integration with all major email service providers for seamless data import and export.  

The tool identifies invalid, catch-all, role based, disposable emails, syntax errors, typos and recognizes if the recipient mailbox is full. It can also analyze email content to prevent spam filters from directing emails to the spam folder.

Pricing starts as low as $0.006 per email, with pay as you go or a discounted monthly subscription. New customers receive 200 free credits.

Email Validator

Email Validator by Byteplant GmbH is a real-time email validation tool that comes in the form of an API. The provider also offers a list cleaning service that removes outdated or invalid email addresses from Excel/CSV files, customer relationship management (CRM) systems, and customer databases. The API provides results in JSON format.

Email Validator’s product provides the following checks: format check, SMTP check, DNS check, as well as free, disposable, and catch-all checks.

Like the four providers above, Email Validator also gives users a free trial to query 1,000 email addresses. Paying customers have to pay around US$3.50 per 1,000 queries.

Email Validator Homepage


Mailgun comes in the form of an API and so is specifically helpful for developers. Its solution is scalable, allowing users to validate as many as 10 million email addresses if need be. It also provides analytics so users can come up with actionable insights. The results are provided in JSON format.

Checks done by Mailgun’s API include format check and disposable check.

Mailgun doesn’t have a free plan offering unlike the other services and charges an average of US$3.50 per 1,000 queries.

Mailgun Homepage


SendGrid comes in the form of an API that users can integrate into their existing systems and applications. The solution is beneficial for developers, startups, high-volume email senders, marketers, and e-commerce companies. The tool provides results in JSON format.

Checks done by the API include format check, disposable check, and MX domain check.

SendGrid offers a free trial and different pricing tiers. The company doesn’t offer a free plan, though. Users typically pay US$3.50 for every 1,000 queries.

SendGrid Homepage

Email verification provides several benefits to companies in various industries, foremost in improving email deliverability primarily for marketing and sales purposes. Of course, not all services are created equal, but there are criteria you can consider to choose one from among the best email verification services featured in this post. To start your journey toward ensuring accurate and effective email validation, make a list of your business requirements and systems/solutions, then consider your budget and feature needs. Choose the one that matches your requirements.