How to identify a reliable email verifier

Renaud Garelli

Last updated on 2 September 2024

Not all email verifiers are created equal

 

As always, when you’re looking for a service on the Internet, you’re spoilt for choice, and the search for an email address verifier is no exception!

But how can you tell the difference between a good email checker and a not-so-good one, when you’re not an emailing expert? How can you be sure that the choice you’re considering is the right one, and not a scam or a faulty service? How do you know if an email verification tool is really reliable? And more generally how does an email verifier work? Well, this article is for you!

 

different mailtester categories


We’re not going to write yet another article comparing one email verifier with another, but rather help you to identify the signs that you can recognize yourself to navigate the world of emailing and email verifier on your own.


Different categories of email verifier

 

The first thing you should keep in mind is common sense: as in all aspects of life, expertise in a field takes time and dedication: you focus on a subject, learn, cross-reference, make connections and eventually have enough experience and know-how to be armed and effective in responding to the given problem.

There’s no substitute for real experience in a field to be truly able to give sound advice and understand the ins and outs of a complex subject. For example, you can’t claim to be an expert in a field if you’re just a reseller… but did you know that 3/4 of the email verifier on the market are actually resellers of white-label solutions? In other words, they’re resellers who don’t know the subject of emailing per se, but who have built a more or less ergonomic website and use a third-party service as an external solution to carry out the technical action of checking emails.
As their aim is often to get a turnkey solution up and running quickly (before moving on to a totally different product), the choice is very often a low-cost solution for the technical connection, and therefore a quality of email verification that is limited, if not downright below the minimum required for some email checkers. The only real focus is on the graphic design of these solutions, as this is what differentiates them from one another, since the quality of the technical service is virtually identical from one tool to another (via the same external validation engine) on this range of email verifier.

These solutions have proliferated over the years, and today make up the majority of email verifiers found in France, the USA and other countries.
In the end, only 1/4 of all email verification software are “home-made” solutions, i.e. they sell a service for which they have their own in-house expertise, and for which they provide a much more nuanced guidance on classification results.

The first thing we advise you to check when choosing an email verifier is whether the solution you’re considering is one of the experts in this field, in order to avoid the use of simple resellers.

But how do you know whether a particular email checker is a real specialist in the field, with expertise and sound advice, and not just another reseller who has simply changed the packaging and doesn’t really know what he’s selling (or even how it works)?

Well, the restaurant analogy is a pretty good way of putting it! When you go to a restaurant, the first thing you look at is the menu. And it’s a well-known fact that if there are a lot of dishes on offer (and on top of that, if they come from very different culinary worlds), then there’s a very good chance that the food offered by that restaurant is bought/frozen and not homemade.
Well, it’s the same thing here: email marketing requires specialized expertise, and so does the world of SMS. So, if a website offers you to check in one place: your email addresses, your cell phone numbers, and your customers’ postal addresses… then you can be pretty sure that this service is a mere reseller and not an expert in the field.

Unfortunately, just because a site offers ONLY email verification doesn’t mean it’s an expert in the field. You’ll need to go beyond this first step, and challenge the solution on technical issues: make a request to support, indicating that you’d like to speak to a technical expert to explain your specific problem (because if you want to use their service, it’s because you have an email deliverability problem).
If you don’t get a reply, or only a reply after several days, or if support only offers you basic answers by email (without the possibility of speaking face-to-face with an expert), then you’ll know that this specific email verifier is more on the side of the resellers than the experts.


Foundations of high-quality email verifier

 

In the email verification business, there are certain fundamental elements that must be respected, and which should be implicit. Unfortunately, with the emergence of “low-cost” solutions that are often opaque in their operation, it’s becoming increasingly difficult for customers to know whether or not they are complying with these mandatory basics.

         low risk email verifier
To help you see things more clearly, here are the elements to which you should pay particular attention when choosing a solution (and on which you should technically challenged a potential solution):

 The very first rule in email verification is that the email actually being verified must not be aware that it is being verified: in other words, email verification must be transparent to the mailbox concerned. The key step here will be the SMTP call made to the mailbox being verified, which will stop BEFORE the email is actually sent.

Note: some poor-quality solutions go beyond this prerogative and actually send an email to each verified address, which is of course a very bad way of doing things, for several reasons: it’s detrimental for the emails checked (which receive spam), it contributes to generate a high rate of unwanted email in the Internet, and it’s legally unauthorized by the various laws that protect end-users from this type of direct marketing (RGPD, CCPA in California, etc).

Verification reliability must be at least 98%:

This point targets two issues:

* the first is to be able to recognize (with high reliability) the various SMTP codes obtained in return (on the SMTP verification phase), and thus determine with good confidence when an email is valid or when it is invalid.

* The second aspect of this foundation is not to randomly classify emails whose status cannot be found. Some emails are particularly difficult to check, as the domains hosting them protect themselves against address verification. If the end status cannot be found, then classification as “undetermined” is the obvious choice, even though some poor-quality mail testers could prefer a random classification (sometimes placing emails in the “valid” category, sometimes in the “invalid” category) rather than admit that they have not been able to determine the true status. This misclassification may result in the loss of many valid contacts, while at the same time introduce bounces on validly tagged emails, which is doubly damaging for the person who asked to check their emails.

Email verification only deals with HARD bounces (and not SOFT bounces):

The primary goal of email verification is to remove all emails that are no longer routable (i.e. emails to which it is no longer possible to send an email, regardless of the sender address used or the configuration of the sending server), which only constitute HARD bounces.

Never use (other than for the requested check) or resell email addresses that have been checked.

Note: some low-cost solutions use a pseudo email verification service as an “bait” to collect a very large number of email addresses. Their ultimate goal is to make money not by verifying emails, but rather by reselling these impressive quantities of emails to spammers afterwards. So beware when the price of a solution is totally uncorrelated with average market prices, because when “it’s too good to be true”, there’s often a scam behind it.

Be able to check at least 80% of all requested emails (for example, don’t provide results where 50% of emails are classified as “unknown email”):

A good email verifier must have an appropriate technical infrastructure enabling it to check a large percentage of requested email addresses: if after an initial test of a solution, the rate of “unknown” emails obtained is quite high, then the tested solution probably does not have enough quality.

Don’t use caching solutions for results:

Some solutions keep previously obtained verification results cached (in memory) for long periods to reduce their running costs, but this is highly detrimental to the validation quality: as emails show rapid status changes, the primary goal of an email checker is to provide up-to-date (and not out-of-date) statuses on the emails tested

 Be able to immediately check email addresses in the majority of countries:

As the email marketing market is international, this prerequisite implies that the email verifier must be familiar with the world’s main email ESPs, as well as the specificities of the main national ISPs in many countries. Some low-quality email verifiers only know the main global email providers (gmail, hotmail, yahoo, aol) and won’t be able, for example, to verify an email address on lesser-known domains, resulting in a high rate of emails classified as “unknown emails” on these ones.

Be able to verify both personal (B2C) and business (B2B) emails:

Some email verification solutions have been created especially for growth-hacking needs, in order to only validate the leads they sell to their customers.
As a result, these kind of email verifier is very often limited in its ability to verify anything other than professional emails. Many of these tools are therefore not “true” email verifiers in fact, as they are unable to check emails on large ESPs such as gmail, outlook or yahoo (and even less so for national ISPs of different countries). This type of “limited” email checker is often found on lead generation solutions that have developed their own in-house validation solution for their own needs, but these ones cannot be compared with “true” email verifier solutions (which can validate any type of email address).

 Guarantee a bounce rate ≤ 3% on emails identified as “valid”:

The primary expectation of a customer who has his email addresses checked is that he will be able to use the results (for his next emailing), without taking the risk of any blockage or deliverability problems.
The results must therefore be reliable enough to ensure that the use of emails classified as “valid” does not cause deliverability problems into the following emailing campaign.
To be sure of avoiding these problems, we consider that the maximum acceptable rate of hard bounces in emails classified as valid should be 3%. This rate enables email routers not to block mailings, and receiving domains (such as gmail, hotmail, etc.) not to degrade the deliverability of received emails.

Be able to evolve towards a higher level of requirement:

Beyond technical verification, the aim of quality email verifiers is to gradually go beyond the purely “functional” verification of the email box: indeed, what’s the point of sending an email to a “technically valid” email address if you know that there isn’t a human behind to look at it?
This email address may have a purpose of its own (e.g. for receiving notifications and other automated actions), but it won’t be useful for email marketing: sending a newsletter or a cold email to it will be of no interest to an advertiser or company. And beyond the fact that it’s of no interest to any advertiser, it’s also money and CO2 consumed, which when multiplied by a large number of emails can lead to significant costs, on financial and ecological point of view.

 

Differences in accuracy of email verification results

 

A particularly interesting aspect to look at is the email classification accuracy obtained in results.

Many email verifiers (including reseller solutions) offer only a basic 3-level classification:

* SAFE emails
* RISKY emails
* UNSAFE emails

This classification, while being easy to understand, does not enable users to make an efficient choice when sending future emails. It’s not clear whether risky emails can be used or not, or where the risk lies.
In fact, some emails classified as “risky” may present more of a bounce risk (which needs to be quantified to estimate this risk), or more of a lower user engagement risk (opening rate, or click rate which is estimated to be lower on these specific email addresses).
It’s also worth noting that the lower the email verifier quality is, the higher the percentage of “risky emails”, as it will also contain all the emails that could not be properly validated by the email checker.

As you have understood, it is therefore important for the email verifier to provide more quantification about the residual risks of checked emails, and this is why good email checkers generally offer several additional sub-categories, allowing much greater precision in the choice of retention (or removal) of the email addresses concerned.

At Mailnjoy, for example, our solution enables detailed classification into 15 sub-categories, far away from the 3 listed above, allowing great flexibility in choosing how to use the results obtained.


Is price a reliable indicator of quality?

 

An in-house good quality email verification infrastructure implies a substantial cost for the company hosting it, which is why the selling price can be an interesting first indicator to look at.
In fact, an email verifier offering much lower prices than all other serious competitors may not be a quality solution, and, as mentioned above, could be a trap for stealing your contacts and reselling them. So beware of offers that seem too tempting, or LTD (Life Time Deal) solutions that are almost never serious or long-lasting.

At the other end of the spectrum, some email verifiers offer rates 3 or 4 times higher than others, without providing any significant difference (in terms of service quality and reliability) to other solutions. These excessive prices may comfort some people who think that this is necessarily associated to better quality, but in reality this is not the case and you could have had an equivalent (or sometimes even superior) service at a much lower price.

These price differences can also sometimes be explained by the fact that email verification market is international, and so a solution that may seem excessively expensive to a European, could in fact represents a fair price for someone living in the USA (or vice versa). As purchasing power and the average price of services are indexed to the relative cost of living in each country, there can be considerable price disparities between services of identical quality but different geographical locations.


Other selection criteria

 

In the case of equivalent solutions in terms of quality/reliability (and at approximately the same price), the choice will often fall on the practical aspect: we will often prefer to choose a solution from our own country to one from a foreign country. Indeed, the simple difference in time zones can be an obstacle if you need to contact customer support on a regular basis, or if working hours are very different from one country to another.

Easy access and responsiveness of customer support are also factors to consider, as are the languages it can be possible to communicate with it.

The final aspect to consider relates to the legal aspect: as email addresses are personal data, it will be necessary to check that the chosen email verifier solution complies with the legal requirements to which the customer must submit in his own country (for example: GDPR for European customers, etc).


Risks summary of poor-quality email checker

 

As you will have understood from this article, choosing the wrong email verification service can have a number of adverse effects for the user.

        high risk email verifier


Here’s a list of possible negative consequences:

Possible stealing of email contacts (which were supposed to be just verified), with use or resale of the them to third-party entities

Possibility of non-compliance with specific regulations (GDPR or other)

Incorrect classification of email addresses in the different categories, which can either cause a too great a loss of contacts (emails falsely classified as “invalid”), or at the opposite a hard bounce rate that is still too high after validation (emails falsely classified as “valid”). This misclassification can lead to a chain of consequences, from a decrease of campaign ROI to deliverability issues.

Too little accuracy on results, ending on too much doubt as to which emails are really usable and which are risky.

Not being able to differentiate emails that are “technically valid” but at the same time which also have little marketing value (possibly managed by robots, autogenerated, etc.), leading to ROI and deliverability issues in the long term.

Little or no user support for results interpretation or for emails classification choices. Not possible to speak with a deliverability expert if the email cleaning is not enough or has not answered correctly to the customer’s initial deliverability problem.

Classification of a large percentage of tested emails as “unknown” status, except for the most common domains (gmail, yahoo, hotmail), which reduces the value of email verification.

Unable to correctly check emails on B2B (business email) or B2C (personal email) domains.

Unable to correctly check emails which belong to complex domains (for example: sfr.fr, free.fr, t-online.de, etc)

Doesn’t differentiate between catchall domains and “protected” domains (which are “fake catchalls” domains and will bounce when an email is sent to a non-existent mailbox).

 May have a high bounce rate (> 5%) even in the “SAFE” category , creating a deliverability risk.


Summary

 

 

best email verifier solution

Now you’ve got everything you need to find THE email verifier which will be your trusted partner in this important email marketing stage which is the email cleaning step!

We hope that these elements will help you avoid the traps that could have led you to choose the wrong solution without really being aware of it, and thus will prevent you from suffering the negative consequences.
If this analysis has interested you and you’d like to go even further in your understanding, we advise you to read our technical article on how to verify an email address, so that the key stages of email verification no longer hold any secrets for you!

If you have any questions about the technical points explained here, please don’t hesitate to contact us in order to talk with one of our technical experts, or to carry out this email cleaning stage with us if you wish!