How To Guide: Validate Email Addresses

How to Verify Email Addresses

You may not realize it, but you probably verify email addresses every day. Whenever you get an email address and send an email to it, you’ve verified that email address.

This works just fine when we get an email address from a friend or get one from a company website.

But if you purchase an email list, or scrape emails from the web, verifying those email addresses may not be so simple. However, if you’ve collected emails in bulk, verifying them before you use them is even more important.

If you’re sending sensitive information, or running cold email campaigns, having invalid email addresses can be bad news.

Also, almost 10% of email addresses entered on forms are invalid. This comes from typos, invalid syntax (like a missing “@” sign), or people entering fake emails to get to gated content without giving up their inbox.

So it’s best to check email addresses before you use them.

Unfortunately, email addresses are slippery things since they’re so easy to create. The fact that there’s a nearly infinite number of possible email addresses makes this even worse. People often have multiple email addresses. Scammers can have thousands.

Fortunately, there are a few methods businesses and individuals can use to verify email addresses.

Here’s what you need to know:

What is Email Address Verification?

First, it’s important to understand what you’re doing when you verify email addresses.

Verifying an email address is simply making sure that the email address exists and can receive emails. But verifying an email address doesn’t tell you who owns that email. You’ll need to do a reverse email lookup to discover that information. We’ll cover reverse email lookups later on in this post.

You should verify email addresses before you use them for anything. Doing a reverse email lookup on an invalid email is a waste of time. Sending marketing emails to invalid emails can hurt your email deliverability.

In short, sending emails to unverified email addresses isn’t worth it.

How to Verify Email Addresses

Since it’s important, it’s worth it to know how to do it. This is true even if you end up just using an email verification service.

But doing it yourself is can be pretty easy, depending on how many email addresses you need to verify and how vital it is that you’re discreet.

Let’s dig into checking email addresses yourself!

Send an Email to The Email Address

The first way to verify email addresses is the simplest. In fact, you’ve probably done this already:

Just send an email to the email address you’re verifying.

Just send emails to verify email addresses!

If the email address doesn’t exist, the email domain will send an automated email telling you as much. Some techies call this a “bounce email.”

You'll get a "bounce email" if the email is invalid or doesn't exist.

Notice that the bounce message says that the email can’t be found or that it’s unable to receive messages. So it’s possible that the email does exist, but the inbox is full or the account is disabled. Either way, sending more emails to an email address like this won’t work.

If the address is valid, you simply won’t get an automated bounce email.

A few things to consider if you’re using this method of email verification:

  1. It’s best not to use your business or professional email if you’re verifying a lot of emails this way. Sending a bunch of emails to invalid addresses could get your email blacklisted.
  2. If being inconspicuous is important, this method probably isn’t for you. If you do hit a valid email address, the person who owns that address will see your email. You can create a dummy email account for checking email addresses. However, there are better options for verifying email addresses without being noticed.
  3. Occasionally, email domains will have an email catch all. This means that they don’t return bounce emails for invalid email addresses. This is very rare. But it can give false positives if you’re checking emails with test messages.

There are other methods, if you’d rather not check email addresses this way. Some are more technical than others.

Ping the Email Address to Verify It

This method of verifying email addresses is a bit more technical and time intensive. But the email owner won’t know you did it.

So this technique can work well for people who only need to check a few addresses and also need confidentiality.

First, you’ll need to enable the Telnet client in Windows or install it for Mac. From there, just open a command prompt. Mac users can use the Mac OS terminal.

Here, all you need to do is check the mail exchange (MX) records of the email domain.

To check the MX records, type this command into the command prompt or Mac OS terminal:

nslookup -type=mx [domain name]

Replace [domain name] with whichever domain the email is located on. If you’re checking, the command would look like this:

nslookup -type=

This command will probably return a few results. There may be more. There may be fewer. But your results should look something like this:

An MX records search will usually get you a few results.

From here, choose one of the servers listed in the MX records. Usually, one without an “ALT” tag is best.

Now, use these four commands to connect to the server and simulate sending an email:

telnet [server] 25


mail from: [dummy email]

rcpt to : [email you want to verify]

So, for my mock Searchbug address, the commands would look like this:

telnet 25


mail from:

rcpt to:

If the email address exists, you’ll get a response like, “OK.” If the email is invalid, the server will return a 550 error like:

The email account that you tried to reach does not exist.”


The email account that you tried to reach is disabled.”

That’s it. This is a good way to verify an email address without alerting whoever owns the email.

However, it’s best not to use this method for mass email verification. Doing this too much can get your IP address blacklisted. That means that email domains might stop accepting emails from your IP address.

If you have a lot of email addresses to verify, or if you’re not comfortable messing with the terminal or command prompt, it may be best to try a different method.

Use an Email Verification Tool

Email verification tools are often free. They also work without exposing you to the email address owner.

Email verification tools are also accurate. False positives are possible, especially with popular email domains like Yahoo!. However, these are uncommon. As you can see, Searchbug easily spotted my mock email address.

Searchbug found that my fake email address wasn't real with a simple email address validation check.

This is the fastest method. Most tools only allow validation of one email address at a time. Email validation services are subject to the same IP blacklisting rules as you are. So they try not to get their IP addresses blacklisted either.

However, it only takes a few seconds to validate an email address this way. That’s far faster than sending emails or pinging email servers.

But, if you have just a bit of information related to an email address, you can use batch processing to get valid emails.

Use Batch Append to Verify Email Addresses

If you have a lot of emails to verify, and have one other piece of information for each email address, you can use batch processing to validate email addresses.

Use batch append services to verify email addresses in bulk.

You can use these pieces of information to validate email addresses in bulk:

  • Name
  • Address
  • Phone number

Here’s how to do it:

Build a TXT, CSV, or Excel file with just the information other than the email addresses. For example, a list of names and addresses would be perfect.

Use associated information to pseudo verify email addresses

Upload your bulk file to a batch processing service, and request that they append emails. This will give you a list of emails that have been matched to the names and addresses. You can double check these emails against your original list of emails.

This isn’t perfect validation. However, this cross checks the emails against two sources. Then you can use a true email validator to check the emails that don’t match.

This is a great way to verify email addresses in bulk. It’s especially effective for businesses that are just trying to minimize the number of emails they send to invalid email addresses.

But there’s one more way to check an email address.

Use Reverse Email Lookup

This isn’t quite the same as true email address validation. This won’t tell you if the email address exists or not. But it’s useful if you want to find out who an email address belongs to.

This is a kind of “soft validation” because most invalid emails aren’t assigned to anyone. It’s also handy if you have an email that you suspect may belong to someone, but need to make sure before you fire off any email messages.

In this case, you’d just take the email addresses, and use them to get names and addresses. That will tell you who owns the email addresses you have. This checks the email addresses you already have against a secondary source so you can be reasonably sure you know who’s on the other end of the email wire.

Verify email addresses by cross checking them against associated information.

This method can also be used with batch append services. So you can use it if you have huge lists of emails to match with names.

So, to sum up, there are a handful of ways to validate email addresses. Sending emails or pinging email servers can work if you need to be sure an email exists.

Batch append and reverse email address lookup can serve as soft email validation. They can tell you if the email has a name and other personal information attached to it, which usually signals that the email address is valid. These methods can be especially effective when they’re paired with true email validation to clean up inconsistencies.

Check out our email validator and our batch append services to find out which method works best for you. Then leave a comment and let us know how it worked!