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Email & Phone Number Verification

58% of businesses lack a formal process for determining the legitimacy of a user at account registration
Image by Solen Feyissa

Phone Number Verification

Phone verification is defined as any of the processes involved in verifying the validity and availability of a number, or the identity of the phone number user.

Numbers can be verified in real-time by checking records in operator home location registries (HLR). These checks can provide detailed number status information – but the most important is whether the number is a valid one. Armed with this information, businesses can decide whether to engage in more in-depth verification.

In-depth verification methods involve user interaction. An example of verification requiring user interaction is common 2-factor authentication.

When signing up for a service, users will be sent a one-time PIN code to their number which they enter when prompted. This can serve as evidence to the service provider that the number is valid and that the device associated with the number is in the user’s possession.

OTP codes are most commonly associated with SMS messages. But there are various channels that businesses can use to ensure prompt delivery of verification codes, including:

  • Voice – this is often the channel of choice for accessibility

  • RCS

  • Chat apps – WhatsApp, Viber, Zalo, KakaoTalk

Another method, and one that doesn’t require user interaction, is silent mobile verification, which works by cross referencing the number with mobile operator data.

This process doesn’t require any effort from the user other than consent – which is great for user experience. In addition to verifying the number, silent mobile verification can be used throughout the customer journey to authenticate actions. Additionally, silent mobile verification can be used as an added layer of security to check whether the SIM card is still in the device. A missing SIM card could be indicative of SIM swap fraud.

This brings us to SIM swap check, which further enhances number verification security. SIM swap check looks at operator records to see when the last MSISDN was paired with the IMEI­. This is a step that helps ensure the user phone number and device are paired.

Why is number verification important?

Number verification is important since collecting and maintaining accurate customer contact databases is a basic requirement for any business looking to build and nurture lasting customer relationships.

If providing positive customer experiences is important to your company – then number validation should be, too.

Because your outreach is only as good as the information in your databases. By checking numbers in real-time at common customer entry points, you can be sure that every message you send customers will hit the mark – and save yourself the costly embarrassment of providing poor customer experience.

Ensuring a valid and verified number is attached to a customer record also helps properly identify customers throughout the customer journey. This helps businesses provide personalized, contextual customer service.

But verifying numbers is important for more than just providing smooth customer experience and personalized interactions.

Number verification can be used to boost security and keep you and your customers safe.

Businesses can protect their customers and themselves by requesting customers to authenticate actions in real-time for important transactions, i.e., cash withdrawals from ATMs abroad or account sign-ins from different geographic locations.

And of course – there’s cost. When businesses target large databases of numbers, they can reduce their overall costs by using number verification to target only numbers that are available. This helps to avoid the costs associated with messaging any invalid or inaccessible numbers.

From providing contextual customer experiences to cost optimization and boosting security for you and your customers, number verification is a must-have. But how do you get started?

How to do number verification

There are several ways to perform number verification. The fastest way to perform number verification in real time is using Number Lookup. This is an HLR-based check that verifies number validity against live operator records.

Number Lookup

When a customer enters their number, your system sends a request through a service provider and checks the number status against operator records. The results can indicate whether a number is correctly formatted, active, reachable – or simply invalid.

These checks can also be performed throughout the customer journey. For example, when making a withdrawal from an overseas ATM, it’s prudent to perform a check on the customer’s number to ensure their device is attached to a mobile network in that country.


Next is number verification via OTP. Once you’ve performed a check and found the number valid, you want to verify that it belongs to the customer.

Depending on the customer’s preferences, you can send them an OTP via SMS or RCS, as well as over chat apps like WhatsApp, Viber etc.

Silent mobile verification

When the customer receives the one-time pin code, they verify ownership and possession of the number by entering it when prompted.

You can continue performing number verification checks throughout the customer journey in an unobtrusive way with silent mobile verification. Silent mobile verification checks the number in the background, ensuring the user’s identity.

By verifying customers in the background, you keep them secure while also providing uninterrupted customer experiences.

Email Verification

Email verification often gets confused with email validation – but validation is a component of the more complex process of verification.

Email verification is the process of ensuring that email addresses you are given are authentic and connected to a real person are genuine, up to date, and reachable.

You can check emails at signup or at any point throughout the customer journey – ideally, before they’re committed to an email list.

But even when you have lists – you should periodically clean them.

This is because, on average, email lists decline by 22.5% each year due to natural subscriber attrition, when people leave companies or change their personal email addresses. Email experts suggest that your lists need to be maintained regularly.

Without regular email list verification, invalid and abandoned accounts will begin to accumulate in your database, resulting in bounce backs and your content not being read.

Why is email verification important?

There are a number of reasons why email verification is important. The first is fraud prevention.

A customer’s email address can serve as a piece of personally identifiable information, which can play a role in identity verification – and fraud prevention. Because of this, it’s important to verify that the user associated with the email address is in possession of and has access to the address. This can be achieved by sending the user a single-use code to help verify the person has access to the address being used at signup.

Next, you want to make sure that people are giving you their correct email address the first time. Unfortunately, this isn’t always the case. In older survey (from 2015), more than 60% of respondents said they will intentionally provide a fake email address.

This can be avoided by implementing email verification at signup to immediately spot incorrect email types.

Email verification at signup will also help to avoid pesky spam traps. These are email addresses used by mailbox providers and blocklist operators to identify senders who aren’t following best email practices. Getting caught in one of these traps can have critical, negative effects on your email sender authority.

Negative email sender authority could result in emails you send to customers landing in the dreaded spam box instead of the intended inbox. Customers will miss important emails, notifications, updates, offers, etc. resulting in lost opportunities, unhappy customers, and poor customer experience.

And last but not least important, verifying email addresses will help keep marketing ROI up. Since email is a cost-effective marketing channel, the cleaner your email lists are, the greater your marketing ROI will be. It should go without saying that emails sent to invalid addresses won’t result in conversions.

Benefits of email verification

There are a few key ways in which email verification benefits businesses. Let’s take a look at the main ones.

Database cleaning

Using email validation tools as a component of verification gives business a way to bulk clean invalid email records, or validate entries in real time.

Whether older email records naturally attritted or were incorrectly entered, email validation can help with both invalid record types.

Cost optimization

By verifying emails and cleaning databases of invalid or unreachable email addresses, businesses avoid the cost of sending to invalid addresses – and with yearly list degradation rates nearly one quarter, your savings are easy to calculate.

Fraud prevention

Email verficiation helps protect against sign-ups by bad actors by identifying patterns in naming, address age, and domain validity. Through timely identification of potential fraudulent actors, businesses can protect themselves and their customers.

How to verify emails

Email verification can be conducted in bulk by cleaning entire email lists – which experts recommend doing periodically due to natural email attrition – or live, one at a time.

Either way, email verification looks at email addresses for:

  1. Invalid and non-existent mailboxes

  2. Syntax errors

  3. Temporary email addresses

  4. Role-based emails

  5. Catch-all domains

Invalid and non-existent mailboxes

This method verifies email addresses before deploying messages by looking at the domain. Performing this check helps you to avoid hard bounces, preserve your sender reputation, and save money.

An example of an invalid or non-existent mailbox would be an incorrect domain, like instead of

Syntax errors

This step looks for errors in the email structure or format made by recipients. Here you can get suggestions for possible corrections.

An example would be “did you mean”

Temporary email address

These are disposable, single use addresses set up for one-time events or for a limited time period. Identify these and remove them from your database to avoid triggering high bounce rates once they’re no longer in use.

Role-based domains

These are emails associated with a company, department or group of recipients instead of an individual.

Anyone signing up to your service with a probably won’t be a single recipient. Remove these from your database to ensure data cleanliness.

Catch-all domains

These are email domains that accept all emails sent to them, regardless of whether the recipient’s address exists. It can lead to a higher risk of sending emails to non-existent or invalid addresses, harming your sender reputation.

Following these steps is a best practice for collecting emails at signup, checkout, or any other point of the customer journey – as well as for purging existing email lists of invalid contacts.

In the next chapter, we’ll look at some more best practices.

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