How to Tell If an Email Address Is Valid | WhoisXML API

Email Verification Blog &
How To Guides to Obtain Email Verification Data

How to Tell If an Email Address Is Valid: 6 Ways to Check and Why It Matters

How to Tell If an Email Address Is Valid: 6 Ways to Check and Why It Matters

Research data indicates that the global email user base increases 2–3% every year, and the number is set to reach 4.4 billion by 2023. That makes answering email marketing questions more crucial than ever. Are all the email addresses in my recipient lists valid? Will my messages reach their intended recipients? Do some of the email addresses in my distribution list have ties to malicious activity?

Each day, users send an average of 54 billion legitimate emails across the globe. Interestingly, a whole lot more malicious spam messages get sent, averaging tens or sometimes even hundreds of billions. When threats are everywhere, the mere act of opening spam could lead to becoming the next victim of phishing or an even more sinister attack.

On the other side of the fence, meanwhile, marketers are worried that their messages may not reach the right people. A lot of organizations suffer from high bounce and low open rates, adversely affecting their marketing efforts. Sadly, no matter how great your campaigns are, if your emails do not reach loyal customers or potential leads, your efforts are bound to go down the drain.

Before diving into how you can determine the validity of email addresses, however, let’s review why the process is important first.

To alleviate these and other issues, organizations need a means to check the validity of email addresses they come in contact with. Email verification using products like Email Verification Lookup or its counterparts, Email Verification API or Email Verification Bulk API, can thus be critical to any company’s successful and efficient operations.

Why You Need to Validate an Email Address

Utilizing an email distribution list can be a powerful marketing strategy for nearly any business. However, it’s not uncommon to build one containing many unresponsive email addresses. Messages sent to these addresses can bounce or simply sit in their recipients’ inboxes unopened. It may not seem like a big deal, but Internet service providers (ISPs) can see this data and use it to determine your domain’s deliverability rating. If your emails bounce too many times, they may decide to classify your messages as spam or even block them altogether. That is where email address validation comes in. It helps ensure that you only send emails to customers who really want to open and read them.

Get Rid of Invalid and Inactive Email Addresses

Your distribution list may contain many email addresses, but some or even most of them may be inactive or invalid. Take a look at how they differ below.

Inactive Email Addresses

An inactive email address is one that its owner no longer uses or has abandoned. Any inactive email recipient can’t view any of the emails you send them. 

Invalid Email Addresses

Invalid email addresses differ a bit. They often get used for spamming or point to expired domains. And there’s not much you can do about them other than removing them from your distribution list. The trick lies in finding illegitimate email addresses, though. You should know that some programs are specifically designed for that purpose. An example would be an email validation API, which can help decrease the number of invalid email addresses used to sign up to your sites that end up in your mailing list.

Both inactive and invalid email addresses translate to unread messages on your part. And when your organization reaches the threshold that ISPs set for bounces, your domain reputation suffers and you risk getting tagged as a spammer. In order to avoid this, it is important to identify these email addresses and clean your distribution list. 

Get Better Marketing Results

Email address validation is also a crucial aspect of effective marketing. Getting rid of invalid and inactive email addresses from distribution lists results in lower bounce rates and higher open rates, improving an organization’s deliverability rating. The practice also helps users avoid becoming part of blocklists that email service providers (ESPs) and ISPs employ. We’ll give you pointers on how you can validate your email addresses in the next section. What’s important is that you now know why email verification is critical in getting the results you’re looking for.

How to Check the Validity of an Email Address: 6 Methods

As mentioned earlier, there are various ways to check the validity of an email address. Some are performed manually while others can be automated. We discussed these in more detail below.

Manual Email Validation Checks

Method #1: Do Google Searches

You can look for the email address owners’ names and contact details via Google searches. However, you may not be able to verify each, as users who are more concerned about their privacy may not reveal their email addresses online. Or, if they do so, the publicly accessible addresses could be secondary or even temporary—email addresses they give out for subscription purposes or even spam traps (which will be discussed later on).

Method #2: Send a Test Message

Using your distribution list as a reference, send an email to each address. Make sure you turn the Request read receipt feature on when composing your test message. You can do that by following the steps listed below, depending on your email service provider (ESP).

For Gmail Users
  • Open Gmail on your computer.
  • Click Compose.
  • Write your email as you normally would.
  • At the bottom right, click More options > More send options > Request read receipt.
  • Send your message.
  • You’ll see any read receipts in your inbox. In some cases, the recipient may have to approve the read receipt before you’re notified.
For Outlook Users
  • Open Outlook on your computer.
  • Write an email as you normally would. Make sure you indicate a subject.
  • In the Options tab under Tracking, check the box next to Request a read receipt.
  • When the recipient opens your email, you should get a notification in your inbox. It will have Read: and the subject line of the email you sent.

The email verification checks above are time-consuming and laborious, as you have to go over your distribution list one email address at a time. Using email validation tools may make the process quicker.

Automated Email Validation Checks

Method #1: Detect Disposable Email Addresses

No reputable individuals or companies are likely to use disposable email addresses. So why bother spending time and effort on low-quality recipients when you could remove them from your distribution list right away for better results?
Email Verification Lookup/API instantly checks if an email address is disposable. It can weed out all temporary email addresses obtained from 10MinuteMail, Mailinator, GuerrillaMail, and other providers. A valid email address, on the other hand, when queried through an email verification tool, should display the following result:

Detect Disposable Email Addresses
Why Detecting Disposable Email Addresses Is a Must

Doing so can help marketers improve their email marketing performance. By making sure that only valid and active email addresses are part of their campaigns, they can protect their email deliverability by getting rid of addresses that are likely to increase their bounce rate.

When integrated into signup forms, Email Verification API can detect disposable email addresses that freemium abusers may use to register for trial periods repetitively (which doesn’t bring in any revenue). Email verification users can even disallow subscribers from using disposable email addresses while registering from the get go.
What’s more, cybercriminals often use disposable email addresses to mask their identities when launching scams. Avoiding these addresses altogether is thus a good cybersecurity practice.

Method #2: Check If an Email Address’s Inbox Can Receive Messages

For an email address to work, it must have access to a corresponding mail server. Users can verify the existence of one by checking for a Simple Mail Transfer Protocol (SMTP) connection and valid mail exchanger (MX) records.

Email verification tools automatically check for these elements with every email address query. A valid email address, therefore, should have results similar to this:

Check If an Email Address’s Inbox Can Receive Messages
Check If an Email Address’s Inbox Can Receive Messages
Why Checking If an Email Address’s Inbox Can Receive Messages Is a Must

For marketers, communicating with existing and potential customers is crucial. But if the email addresses in their distribution lists don’t have corresponding inboxes, their messages simply won’t reach their intended audiences. And so, these email communications, whatever their purpose, are bound to bounce as well. In turn, a continued increase in bounce rate is bound to heighten their chances of landing on a spam blocklist if not alleviated.

Method #3: Catch Syntax Errors

Every email address needs to follow a format specified by the Internet Engineering Task Force (IETF). Any address that fails to do so is deemed invalid. Ideally, an email address should have three components:

  • Local address (typically the inbox owner’s name)
  • Domain name (usually the organization’s name)
  • Domain identifier (the top-level domain [TLD])

In the email address john_doe@company[.]com, for instance, “john_doe” is the local address, “company” is the domain name, and “.com” is the domain identifier.

When queried on Email Verification API, a valid email address should have this result:

Catch Syntax Errors
Why Catching Syntax Errors Is a Must

Sending emails with misspellings and formatting errors can result in one of two things—they will either bounce or be directed to a catch-all inbox (which will be discussed in more detail in another section). Whatever course of action you take, however, the end result is the same—the email won’t reach its intended recipient. To marketers, that means a lost business opportunity. To security teams, that means an increased likelihood of landing on someone’s blocklist.

Method #4: Determine Catch-All Email Addresses

Many companies use catch-all email addresses to ensure that none of the messages intended for a staff member falls through the cracks. Catch-all email addresses accept emails meant for even misspelled local addresses (i.e., wrongly spelled employee or department name) or domain names. So when a prospective customer sends an inquiry to, say, slaes@samplestore[.]com instead of sales@samplestore[.]com, Samplestore will still get the message despite the misspelled department name if it uses a catch-all email address.

Email verification tools can help marketers and security professionals alike in that it checks if an email address is a catch-all. On Email Verification API, a non-catch-all email address would return the following result:

Determine Catch-All Email Addresses
Why Determining Catch-All Email Addresses Is a Must

While using catch-all email addresses prevents businesses from missing out on opportunities, it can also prevent marketers who are specifically targeting an employee but misspelled his/her name, for example, from communicating with the intended recipient. On the other end of the spectrum, meanwhile, cybercriminals are also fond of using catch-all email address lookalikes for their schemes.


All that said, the question of how to tell if an email address is valid is indeed a critical one to ask. Organizations need to subject every email address coming their way to numerous tests if they want to ensure good deliverability, keep their email reputation intact, as well as steering clear of threats that rely on insufficient email security.

Whether for improving marketing results or mitigating security risks, they can rely on solutions that allow quick checks on any email address, such as Email Verification Lookup and Email Verification API.

Try our WhoisXML API for free
Get started