How to Validate Email Address for Improved Email Deliverability

November 11, 2023
How to Validate Email Address for Improved Email Deliverability

Are your emails reaching their intended inboxes, or are they being shunted aside into spam folders? Or worse, bouncing back altogether? Although our campaign goals differ when we send emails, one common goal is for the mail to reach the right address. This may seem an easy task, but emails often end up in the spam folder. This isn't good for your business and can negatively affect your email reputation. To avoid this, you need to validate email address. What is email validation and why is it important is the topic of our article.

Why is email validation important?

Email validation is extremely important for deliverability, i.e., efficient delivery of email messages. If the email addresses you have on your list are invalid or incorrect, sent messages will "bounce,"  which can negatively impact your sender reputation. In its simplest form, email validation verifies whether an email address is valid and deliverable. And why is it important?

Reducing the bounce rate is the first step towards improving the sender reputation. ISPs track how many of your emails reach end users. So, if you regularly send emails to invalid addresses, the ISP can mark you as a spammer. That will reduce the chances that your future emails will end up in the inbox.

Besides, if your email list contains only valid addresses, you will have more accurate and relevant reports. You will know exactly how many people open your emails, click on links, etc. These metrics are very important because you adjust your campaign based on them.

Last but not least, this is how you can save resources. If you send emails only to valid addresses, you will save both time and money.  You will not waste your resources on sending messages you know will not be read in advance.

The consequences of sending emails to the wrong addresses can be significant. Not only do you waste time and resources sending these emails, but you also risk your reputation as a sender. Also, incorrect report information can lead to incorrect conclusions and poor marketing decisions. So, email address validation is key to successfully running email marketing campaigns.

How do you validate email addresses?

Now that we know this, it is clear that having a clean list and maintaining it in such a way is necessary. A clean email list has gone through the validation process. That means all addresses on the list are confirmed as legitimate and active and can receive an email message. But how can we know this?


First, it is necessary to understand the process of validating email addresses. Here's how it works.

The email validation process

Email validation is the process of checking whether an email address is valid and can receive emails. This process usually involves several steps: 

First step: Syntax check

First, let's understand the syntax of an email address. 

The syntax of an email address refers to the structure, i.e., the format that the email address must follow. The standard syntax of an email address includes the following parts:

  • Local part: This part is located before the '@' symbol and can include letters (a-z, A-Z), numbers (0-9), dot (.), plus (+), dash (-), and underscore (_). The local part cannot start or end with the dot symbol (.)
  • @ symbol: The '@' symbol is a key part of every email address. It divides the address into the local and domain parts. 
  • Domain: The domain can be found after the '@' symbol. It consists of the domain name (such as 'gmail,' 'yahoo,' etc.) and the domain extension (such as '.com' '.net' '.org'). 
  • Domain extension: This part comes after the dot in the domain part and usually has 2 to 6 characters

According to this syntax, an example of a valid email address would be ''. Any email address that does not follow this syntax is considered invalid.

Syntax check is an important step that examines whether the format of the email address is correct. An email address should contain one '@' symbol, a domain (e.g., gmail, yahoo), and a domain extension (e.g. .com, .net). Also, it should not contain invalid characters. For example, the email address '' is in the correct format, while '' is not.

A correct email address is the first step towards ensuring our email reaches the recipient.

Second step: Domain check 

Once we have checked that the format of the email address is correct, the next step is to check the domain. This step involves checking whether the domain exists and can receive emails. For example, if the email address's domain is,' the system would check whether that domain exists and is active. 

Besides, you can check this using online tools like MxToolbox, where you enter the domain and see the results. If the domain has an MX record, it can receive emails. The email address is considered invalid if the domain does not exist or is inactive.

Third step: User check:

The third step in the process of validating email addresses is user verification. This step focuses on the part of the email address before the '@' symbol. It is often referred to as the username or local part of the email address.

When you enter an email address, the validation system will check if the username you have provided exists on a certain domain. For example, if you enter '', the system will try to find the username' name.surname' on the '' domain.

This check is usually done by communicating with the email provider's servers. The validation system will send a query to the server to check if the username' name.surname' exists. The email address is considered valid if the server confirms the username exists. The email address is considered invalid if the server cannot find the username. 

It is important to note that this check can be complex. Some email providers do not allow them for various reasons, including Privacy and security. In such cases, the validation system can rely on other methods. Such as checking the syntax of the email address and the domain to determine whether the email address is likely valid. 

Each step is important in ensuring that the email address is valid and can receive emails. This process helps reduce the bounce rate, improves sender reputation, and increases the efficiency of email campaigns.

Methods you can use to validate email address

Now that we understand the process of validating email addresses, we can discuss different methods. Each of them has its advantages and drawbacks. Choosing the best method is certainly easier if you understand them all.

Basic Validation: Format and Syntax Check 

The simplest method of validating email addresses involves checking the format and syntax of the address. This ensures that the address adheres to the standard format, i.e., username@domainName.tld. Although this method can identify obvious errors such as missing '@' symbols or invalid characters, it cannot confirm whether the email account is active or capable of receiving messages.

SMTP Validation: Explanation and Its Importance


SMTP (Simple Mail Transfer Protocol) validation goes a step further in verifying email addresses. It involves sending a so-called 'handshake' message to the mail server to check whether the mailbox can receive mail. 

The 'handshake' message is part of the communication protocol used when establishing a connection between two systems. In this case, it is between the server sending the email and the server receiving it. This process is often also called an "SMTP handshake" in the context of email validation. 

Here's how it works:

  • The server sending the email (in this case, the email validation server) initiates communication with the receiving mail server. 
  • The receiving mail server responds with a status code indicating whether it is ready to accept the email. 
  • The email validation server then sends the 'MAIL FROM:' command, which identifies the source of the email. 
  • The receiving server confirms receipt of this command. 
  • The email validation server sends the 'RCPT TO:' command, which identifies the target email address. 
  • The receiving server confirms that the email address is valid (responding with a status code indicating success) or denies receipt (with an error code).

It is important to note that the actual email message is not sent during this process. The 'handshake' message is a way to check whether the receiving server would accept an email for the given address.

This process allows SMTP validation to check not only whether the email address is correctly formatted but also whether it is connected. The advantage of this method is that it is extremely efficient. But, it can require quite a bit of time and certain technical knowledge.

The Role of the Double Opt-In Process in Email Validation 

The double opt-in process is a very efficient way to validate email addresses. When users sign up, they are sent a confirmation email with a link. Only after they click on this link does their email address become validated. This simple process ensures confirmation that the email address exists. 

But more importantly, it confirms that the address belongs to someone who has agreed to receive your emails and is interested in them. This method significantly reduces the chance of sending emails to non-existent or incorrect addresses.  It also ensures a higher percentage of opened emails.

Using Professional Email Verification Services: Advantages and Disadvantages

If you have a large email list or need to be more technically savvy, the solution might be to hire professionals. Professional email verification services combine multiple validation techniques. That includes syntax checking, SMTP validation, and checking against known lists of bad addresses. If you want a comprehensive solution for checking and cleaning your company's email list, they offer it.


  • High accuracy
  • Saves time and effort
  • Can handle large volumes of email addresses 


  • It can be expensive, especially for large email lists 
  • Privacy issues as you share your email list with a third-party

Any of these methods will help you improve your email delivery and thus increase your email campaigns' efficiency.

Email address validation is not just an optional step when you start an email campaign. On the contrary, it is the foundation of successful email marketing. Validation is necessary to ensure efficient email delivery, improve your reputation, and gain insights into your campaign metrics. Validation is a process with different methods to validate email addresses. Whichever you choose, be assured that the time and resources invested in email validation are well spent. Remember that a clean email list is the foundation of a successful email campaign. Therefore, email validation should be a regular and important part of your email marketing strategy, and you will soon see its positive impact.

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