How Email Verifiers Work and Why You Need One

Linked Helper
Jun 27, 2018 · 10 min read

Every marketer who has run an email or outreach campaign at least once, knows that email marketing is a proven and precise marketing method, the best thing about it is metrics — every step of your email campaign can be easily measured.

The most well-known steps in every campaign are delivery rates, open rates, click-through rates and conversion rates. These measure the overall success of any campaign. Management and smart optimization of the campaign allows you to control any and all of these metrics, thus bringing your results to new heights.

Unfortunately there is a metric many people often forget about, it measures the very first step of your email campaign — email address validity. The more accurate your initial email list is, the better your campaign’s performance will be. More importantly this small metric can improve your results dramatically or completely ruin the whole campaign.

As you can see the importance of email verification should not and can not be underestimated.

This article will explore what email verifiers are, what’s behind the software or service, and how they improve the results of email campaigns. We will show you an actual experiment of email verification process, and teach you how to choose an optimal email verifier for your marketing needs. Let’s get this verification party started.

What are email verifiers?

Email verifiers are desktop tools or online services (both software-as-a-service or plugins) that allow marketers and salespeople to verify a single email address or a whole list of email addresses, and be sure the contacts exist, working and valid.

Nowadays most email verifiers are represented as online services, and the reasons are quite simple — it can be accessed anytime, anywhere and from any device. They don’t require any additional resources besides an internet connection, and can be easily supported and updated by the developer and vendor of the service. But the most crucial reason is that you can use multiple stable servers for verification, and do not run the verification process by using your own IP address.

The best example of a modern and feature-rich email verification service is Snovio Email Verifier — it’s an online verification service that allows users to verify single emails and email lists in bulk, you don’t even have to leave the current tab in your browser, because it works as a plugin (Chrome Extension).

Now that we have clarified what an email verifier is, let’s take a look what’s behind the system and how it actually works to verify and validate all the email addresses.

How email verification works

Even though many people have heard about email verifiers, or maybe used some of them, not all clearly understand the technical aspects of the service. We will show you how it works by describing the main technological features and verification steps — this will allow you to easily understand how email addresses are validated.

The main email verifier features and validation steps:

Step 1 — Syntax check — this is the core feature, the first step of validation for all email verifier services. Syntax check makes it possible to check whether an email address is spelled correctly — has no spaces, commas, and all the @s, dots and domain extensions are in the right place.

Step 2 — Domain check — the second step of the email verification process. Domain check allows you to be sure the domain name the email address is hosted on actually exists, is registered and working properly on the hosting domain.

Step 3 — Email ping — this is the most sophisticated step of email verification. Email ping is the technical process of an email verifier service pinging the exact email address with an EHLO message, then awaiting the response from the email server. The received server-response will confirm the email address actually exists on the server and is active.

Different email verifier services can provide users with all or just some of these verification mechanisms. For example, Snovio Email Verifier uses all of the core methods granting one of the highest validation rates, while a popular competitor like does not even verify personal emails hosted on Gmail. All the features described above are a must-have for any modern verification service, and all of them matter!

Reasons to verify emails

There are quite a few reasons why an email address may not be working anymore or be considered invalid. Some reasons are technical, others relate to the human factor — things change, anything can happen. Let’s take a look at the most common reasons you should always verify your email lists.

  1. Person changed email provider/service. Probably one of the most common reasons. Here is a quick example — a person used their email provider’s email service (a local one) and then switched to Gmail, or vice versa. Or a person switched from one popular inbox provider to another. Most importantly, even if the first email address is still “active”, a message sent to it will never be read.
  2. Person changed email ID within the same provider. Another common scenario — a person keeps using the same email provider, but switches to another account with a different email address. Let’s say the email address used first was and then person switched to a more appropriate email address at
  3. Person switched position within a company. In many companies, especially bigger ones, employees have different email address types according to their positions. Low-level employees, mid-level employees and C-level employees usually have different formats of email addresses, and if the person switched positions from a mid-level manager to a C-level decision maker, or from a hands-on specialist to a manager, the previous email address can easily become invalid, thus making your email messages bounce.
  4. Person changed jobs. An extremely common cause of undelivered messages, especially in B2B niches, where many specialists and decision-makers change jobs once every few years. When a person leaves a company, their email becomes unreachable or is simply redirected to another person replacing them. Though your message may be delivered you won’t reach the person you want to reach.
  5. Domain is dead. That’s a common reason, and it’s quite technical. If the website is unreachable, the domain is dead, or a mail server on the domain’s server is down, you won’t be able to deliver your message to the recipient. It is a good indication that the company is out of business, so make sure to filter out email addresses that are invalid for this very reason.
  6. Public email provider is dead or down. If the email provider is out of business or the servers are down. there is no chance to deliver your email message to a recipient. Online email providers can close business, while sometimes they just experience technical problems with servers (especially smaller email providers).

The reasons are quite different, and all of them are checked by using different technical mechanisms within an email verifier tool. It’s important to make sure your email verifier supports various verification methods (such as syntax check, domain check and deliverability check). These are core features of Snovio Email Verifier that can easily verify both single emails and large lists, personal emails and corporate ones, hosted on public servers and on private ones.

What emails should be verified?

That’s a good question. The answer is simple — every email address and email list should be verified. You saw the reasons described above, and you clearly understand that any of these can happen anytime. So the more often you verify your existing lists the better, and always verify your new email lists.

Some people verify only new email lists, or email lists generated from untrusted sources, which is good, of course, but does not eliminate the risk completely. You should always verify new email lists, even those bought or generated from highly trusted sources (such as expensive third party databases and vendors). You should also validate your existing email lists from time to time (once a month is enough).

Email verification is a must-have process, and you will see more proof of how important it is and how much time and money it can save you.

How to choose an optimal email verifier

Now that we’re clear with what an email verifier is, how it works and why we need to verify emails, let’s move on to some quick guidelines on how to choose an optimal verifier and what it should contain.

  • Online Service — the optimal option is an online email verifier, that works as software-as-a-service (SaaS). It doesn’t require any of your computer resources, it can be accessed anytime, anywhere and from any device, and you don’t use your own IP for the verification process (instead it uses the service’s IPs which work way better).
  • Scalability — your email verifier service should be able to verify both single email addresses, and large email lists. Though checking bigger email lists takes longer, it is still done almost instantly.
  • Corporate and personal emails — your email verification tool should be compatible with verifying both corporate email addresses located on the company’s domain and private email addresses located on public email providers (such as Gmail, Outlook, Yahoo).
  • Multiple verification mechanisms — you cannot rely on just one, your email verifier should allow you to verify emails by running various validation methods, such as syntax check, domain check and email server ping.
  • Integrations/Connectivity/All-in-One — these are important features, because email verification is used within an email marketing process, and it’s good to have your email verifier connected to or integrated with other modules, such as email generation tools, email sending tools, email list management tools and more.

Let’s take a look at the example below, and compare 2 competitive products, Snovio Email Verifier and Email Verifier, as these are both quite popular on the market.

Practical part — let’s run an experiment!

Now let’s get to the most interesting part — a practical experiment where we will show you how an email verifier saves you time, money and optimizes your resources and the overall process of email/outbound marketing.

For this experiment we generated 1000 leads (email addresses) from various sources and then verified them to show you how an email verifier cleans a list and improves overall campaign metrics. See the documented process below.

Toolset we are using:

  • LinkedHelper — a tool to generate leads on Linkedin. LinkedHelper allows you to easily get hundreds and thousands of contacts (email addresses of Linkedin users), by sending personalized invitations to 2nd and 3rd contacts.
  • Snovio Email Finder — a tool to generate leads on Facebook, Twitter, other social networks, and from visited websites.
  • BuiltWith — a database of businesses using specific technologies. This tool allows you to get contacts of companies/people who use specific technologies on their websites, such as shopping carts, analytics tools, marketing tools, CRMs and much more.

Number of emails generated:

  • 300 emails generated on Linkedin (with the help of LinkedHelper)
  • 200 emails generated on Facebook
  • 200 emails generated on Twitter
  • 150 emails generated from visited websites
  • 150 emails generated by using BuiltWith database

As you can see, the sources we generated email contacts from are pretty different, but thanks to the tools described above getting 1000 leads was supereasy. It took us 2 hours, including coffee breaks. The email addresses generated above consisted of both corporate emails (hosted on company’s domain) and private ones (hosted on public server providers).

After verification 320 emails turned out to be invalid. That’s 32%! These included dead domains, non-working servers and non-active email accounts. The verification process took us 3 minutes 20 seconds.

Tools we used for generation do not extract incorrectly spelt email addresses, so we saved a bit on checking for the incorrect syntax, which is good.

32% is an okay number of invalid email addresses, whether they are generated on the web or from a database. But how much does it cost you as a specialist or a business owner? Check out the calculations below.

It’s worth every single penny

Let’s talk numbers and business now.

  • $0.006 — average price per email address verification across multiple verification tools that are available on the market.
  • $0.001 — price per email address verification through Snovio Email Verifier.
  • $0.015 — average price per email delivery across multiple email senders that are available on the market (both bulk email sending services and smart outreach tools).

It costs $6 on average to verify 1000 emails, or $1 with Snovio Email Verifier.

Now we have 680 valid email addresses to use in our outreach campaign. The best thing is that we don’t need to deliver our message to those 320 invalid email address. We spent $1 to verify 1000 emails, and saved almost $5 ($4.8 to be accurate) on email delivery.

Imagine if you run campaigns on a daily basis, or you deliver to more recipients — that’s a decent amount of money saved! By verifying email lists an average company that often runs email campaigns can easily save $100–300 a month.

But you are not just saving money, you are saving another important asset — your reputation, and your technical reputation as a sender.

By verifying email lists and delivering your email messages to valid, existing and working email addresses you improve a lot of parameters:

  • Delivery Rate (or Bounce Rate)
  • Open Rate
  • Click-Through Rate
  • Reply Rate
  • Conversion Rate

High metrics can boost your technical performance and overall business results, and low ones can ruin all your efforts.

As you can see now, email verification is a win-win process — it saves you money, saves your reputation and saves time. It is worth every single penny spent!

Have a great day, and keep those metrics high.

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