Real-time email verification is a must for every business looking to improve their email marketing metrics and ROI, and as you can see, an email validation service can make this process so much easier.

Back in the day, a sales manager rested their laurels on the size and value of their address book. Direct to home mail brought in lists of people who could then be sent letters asking them to buy. Now, companies judge themselves by the size of their email database—but how do you put a value on that list of emails? What’s the benefit of doing so?

Well, not validating your email list can lose you money. Plain and simple. According to Econsultancy, 74 percent of marketers believe email will be the highest return on investment, still, in five years. Staying on top of having a clean, validated email list is one of the most important things you can do to get the most money out of your highest return on investment.

But, every month, roughly two percent of the email addresses in your list starts to decay. It’s time to verify your emails straight away—and here’s how.


Before we get into how to verify your emails, let’s discuss what exactly it means to do that.

Sooner or later, every business will need to verify their email addresses. They will need to do this to decrease bounce rate, purge old or unresponsive email addresses, or prevent their domain from appearing on spam reports due to bounce rate or unresponsiveness.

Email verification can be done in several ways—which way will depend on the type of your business.

Real-Time Syntax Verification

Checking an email address for syntax accuracy is probably the most basic form of email validation. For instance, mike@example is easily identified as invalid because it’s missing its extension (.com, .org, etc.).

Again, doing this manually would be a large burden, which is why most email validation services will include syntax verification. There is also a multitude of open-source libraries purposed in many languages.

SMTP, Simple Mail Transfer Protocol, is something that’s done on every single email “transaction.”

You can, using a telnet command prompt, use SMTP to check if a user for a given email address exists or not without ever sending an email. The following image shows you how to do that:

How to Use Telnet to Test SMTP Communication Microsoft Docs
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Simply run that command for every email in your list.

Oh, wait, that would take forever. That’s why most businesses worth their salt choose to use an email verification service, like Email Oversight.

SMTP, while effective, is far from comprehensive—for example, some mail servers will accept any message despite if it exists or not, which is why you should combine SMTP with another form of email validation.


While considered to be a bit invasive, confirmation email verification is the most accurate way to tell whether or not an actual human eyeball will view your email.

This can be odd for an existing email list since it will send an actual email asking the user to click a link to confirm. So, this method can be labeled as 100 percent effective, if and only if, the user clicks the link.

Therefore it’s much more beneficial to use real-time email validation, which we’ll get into later.


Now that we know what email verification is and how to do it, let’s now discuss why you should clean your email list.

It’s widely accepted that up to 15 percent of all email addresses are invalid. That means that your email is not reaching one out of every seven people if your list has not been cleaned up.

email hygiene EmailOversight
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If you’re smart, you should validate your email list before each and every campaign, and here’s why:

Lower Bounce Rates

Wouldn’t it be great to get rid of bounced emails? For you, it would rid yourself of another marketing metric, but there’s something far more important about bounce rates.

Email service providers (ESPs), email blacklisters, and anti-spam services love bounce rates. The higher that bounce rate, the more likely your domain is to appear on blacklists and spam filters. ESPs, additionally, prioritize lower bounce rates which can raise your email to send reputation.

Sender Reputation

As mentioned, a higher bounce rate places you at more risk of getting blacklisted or marked as spam. This lowers your sender’s reputation, which can eventually get your kicked from your ESP. Cleaning your email list before each campaign greatly protects your sender reputation and can increase your interaction and response rate.

More Return on Investment

If your email is reaching more inboxes and is sent from a domain with a positive sender reputation, the more likely you are to receive interaction or response. This translates into a higher ROI on your email campaigns.

Metric Performance

If you’re the one in charge of your company’s email campaigns, positive metrics can get you that promotion. With a scrubbed email list, you get all the aforementioned benefits as well as more accurate open, click-through, and conversion rates.


As mentioned, two percent of the emails in your email list starts to decay, giving you inaccurate numbers and lower conversion rates.

But why does an email list get dirty in the first place?

Abandoned Accounts

We’re all guilty of creating an email address for the purpose of not getting spammed. How often do you check that account if it’s not for clicking one of those confirmation links? The answer is probably never.

Now, how many of these abandoned accounts are on your list? You may never know as many of those accounts are still in good standing, just never used. This could make your email list seem larger than it is since the point of sending your emails are to have them read.

As mentioned, two percent of the emails in your email list starts to decay, giving you inaccurate numbers and lower conversion rates.

Job Changes

It’s the millennial era and people are changing jobs more than ever. A survey conducted by Career Builder has shown that 21 percent of people are looking to find a new job in 2016.

If a person leaves a job, their email changes and the one they’ve been using (the one in your list) is no longer deliverable.


Typos, or invalid form entries, have increased with the onset of mobile (looking at you, auto-correct). Typos cause the email address of a potential customer to be invalid at the onset of signing up.

The inevitability of these three things can be stemmed by using email validation at the very start of your sign up or import process sometimes referred to as real-time email verification.


Syntax errors, abandoned accounts, all the reasons for why an email list is invalid that we talked about can be prevented with real-time email verification.

Besides validating your email list before each campaign, real-time email verification is the best way to ensure your emails reach more eyes than ever before.

Real-time email verification happens when you add an email validation service’s API key to your ESP. At that time, opt-in forms on your site immediately are screened for validation, including for syntax, STMP, & double opt-in confirmation emails.

Using real-time email verification can:

  • Reduce bounce rate
  • Improve click-through rate
  • Skyrocket open rates
  • Reduce the cost of sending email campaigns
  • Save time screening lists manually
  • Better identify potential leads and segment customers
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