Email validation is essential to ensure that addresses are valid and active, avoiding delivery issues and protecting the sender's reputation. Initially, it focused on syntax, but methods like SMTP Ping proved ineffective and were considered spam. Best practices include using email validation tools, autocomplete, double opt-in, and regularly scheduled validations to maintain a clean email list and prevent deliverability issues. These tools save time and money, reduce bounces, and improve email delivery.

Examination of Email Validation Methods

Email validation has gone through various phases, from complying with regular expressions to today's sophisticated tools. It is crucial to understand the fundamentals before examining the history of validation methods and best practices.

Email Validation: What Is It and Why Is It Important?

Email validation is a technique to ensure that a recipient's address is valid and active. By verifying that the address belongs to the intended recipient and that they consent to receive such communications, certain techniques go a step further in validating an address. During the process, you will protect your reputation as a trusted sender with Internet Service Providers (ISPs) by removing dangerous and invalid addresses from your list.

Before sending marketing and transactional messages, double-check users' email addresses. This increases the likelihood of your communications reaching readers' inboxes. Campaign metrics are also more accurate and provide more insights for future data-driven decisions.

Initially, Syntax Validation Was Used

Email validation has traditionally been as basic as checking the syntax of an email address. The local part, the @ sign, the domain, and finally, the extension (.com, .org, etc.) are the fundamental components of an acceptable email address. To help standardize various syntaxes, RFC (Requests For Comments) standards were published to specify which characters would be allowed for the local and domain sections. As a result of the eventual expansion of these RFCs, open-source tools were needed to help validate email syntax in various languages.

Obvious spelling errors, such as, are a crucial part of syntactic validation. It is still recommended to check the current list for this type of problem.

SMTP Validation Command and the Spammers' Attack

Internet Service Providers (ISPs) began integrating email address validation functionality after realizing the need for assistance in the process. Therefore, "VRFY" (also known as Verify) was developed as an SMTP command that allowed senders to inquire about the validity of an email address to a receiving mail server. With the intention of using VRFY to bring harmony and order to the galactic Internet, it quickly slipped into the hands of the dark side spammers. Email address validation became a mess after ISPs' managers deactivated VRFY due to widespread exploitation of this feature.

SMTP Ping (Spammers' Threat)

After the disappearance of VRFY, senders ingeniously created SMTP Ping, an alternative technique to check the validity of an email address. To determine if an email address was active, SMTP Ping was used to check it with a distant mail server. The connection to the remote mail server of the Internet Service Provider (ISP), such as Gmail, would be established as if an email were being sent but would abruptly cease without actually sending it.

The Downside of SMTP Ping

Interrupted handshaking, commonly known as SMTP Ping, is considered spammer behavior by ISPs. By observing conversation patterns, ISPs can quickly determine that you are simply verifying the legitimacy of email addresses. Calling repeatedly and hanging up without sending any messages (or very few) results in entries in their mail servers' logs.

Due to past experiences with SMTP VRFY, this kind of action is now recognized as spam. ISPs are strictly enforcing their policies against this activity. For example, Microsoft views this behavior as hostile, and Hotmail identifies SMTP Ping as evidence of an attempt to collect a directory. A hard block will usually be dropped on all connections from the transmitting IP address when an SMTP Ping attempt is in progress. Both ISPs and blacklisting operators detest SMTP Ping. If it continues this way, you are almost certain to end up on a blacklist.

Furthermore, many ISPs delay recipient validation until after the conversation with the server is finished, leading to acceptance without confirmation of the email address's legitimacy—a false positive. Some ISPs use greylists to protect recipients. Emails from unidentified senders are rejected by the receiving server using greylist protocols. As a result, SMTP Pings will falsely indicate that an email address is genuine by returning an error response.

In summary: It's a poor and unreliable practice.

Best Practices for Email Validation

You can take several steps to ensure the viability of your email validation strategy, including:

  • Consider adding an autocomplete function to your email input field that includes known extensions like, such as Allowing users to choose from preformatted entries reduces the likelihood of errors.
  • Consider using double opt-in: Sending an email in response to a user's request asking them to confirm their email complies with the law in some markets and provides validation.
  • Take advantage of technology: Various email validation programs offer a quick and cost-effective approach to improving communication and maintaining good relationships with ISPs.
  • Establish a routine: While it may be tempting to validate emails only when running a mass sending campaign, regularly scheduling validation may be the better option. Consider how often and from where emails are added to your list: the more options there are to capture contact information, the more chances there are that addresses are not valid.

Why Use Email Validation Tools?

Using email validation tools has many advantages, including the following:

  • Saves time, as these tools, like Valid Email, use automated validation methods that reduce the time needed for manual searches.
  • Saves money: By avoiding unnecessary expenses, a clean email list with authentic addresses reduces bounces and increases return on investment.
  • As a result, you stay off the blacklist: Spam complaints can lead to message and sender blocking. This decreases with the use of validation tools.
  • Improves deliverability: Deliverability is important for promotional and transactional communications because readers must receive them before responding to them.
  • Provides immediate results: Higher-quality contact information is obtained by confirming instantly through various stages of the buyer's transaction.


Email validation is a crucial process to ensure that your messages reach recipients' inboxes and to maintain a strong reputation as a trusted sender. If you want to ensure that your email list is clean and ready for your next campaign, we recommend signing up on the Valid Email page, where you can get up to 1000 email validations for free. Don't miss the opportunity to improve your email deliverability and maintain effective communication with your contacts.


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