5 Ways to Implement Email Validation in PHP

Validating email addresses in PHP is a fundamental step for data integrity and user communication. We'll explore five different validation techniques, complete with code examples. You'll see the common pitfalls of traditional approaches and learn how Abstract API provides a more robust solution to overcome these challenges.

PHP Email Validation Methods

Here are four common methods to perform email validation in PHP. Each approach has a distinct mechanism for syntax and format checks, from built-in functions to comprehensive libraries.

PHP's filter_var() Function

This method uses PHP’s internal parser for validation. It applies the same EBNF standard that the engine uses when it constructs outbound addresses. This process correctly rejects elements like comments or quoted strings that lack proper escapes. A community discussion notes its behavior.

$email = trim($input);
if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
    // The email address is valid.
}

IDN-Aware Validation with idn_to_ascii

This technique handles Internationalized Domain Names (IDN). The process first splits the local part from the domain. Next, it converts the domain to its ASCII equivalent, known as Punycode, so the validator only processes LDH characters. You then re-assemble the address and run `filter_var`.

This approach works for addresses with UTF-8 characters like `用户@example.cn`. It requires the `intl` extension and at least PHP 7.3. Some community notes show `filter_var` alone fails without this conversion.

list($local, 
$domain) = explode('@', $email, 2);$domainAscii = idn_to_ascii($domain, IDNA_DEFAULT, INTL_IDNA_VARIANT_UTS46);
$emailReassembled = $local . '@' . $domainAscii;
if (filter_var($emailReassembled, FILTER_VALIDATE_EMAIL)) { 
  …continue…
}

The Egulias/EmailValidator Library

This option is a Composer library that offers RFC-complete validation. It implements RFC 5321, 5322, 6531, and 6532 grammars and understands UTF-8 characters throughout the entire address.

The library provides multiple validation strategies, such as `RFCValidation`, `DNSCheckValidation`, and `SpoofCheck`. It is also possible to chain checks together with MultipleValidationWithAnd.

composer require egulias/email-validator

use Egulias\EmailValidator\EmailValidator;
use Egulias\EmailValidator\Validation\RFCValidation;

$validator = new EmailValidator();
if ($validator->isValid($email, new RFCValidation())) {
  // The email is valid according to RFC standards.
  …continue…
}

Format Check with DNS MX Lookup

This method adds a reachability check after a syntax validation. Once the email format passes a check from one of the previous techniques, you can verify the domain's mail exchange (MX) records.

The `checkdnsrr()` function performs this lookup. A successful lookup indicates the address is at least routable and helps catch obvious domain typos. The OS resolver often caches the result.

list(, $domain) = explode('@', $email, 2);
if (checkdnsrr($domain, 'MX')) {
  …address is at least routable…
    // The domain has MX records and is likely able to receive email.
}

Challenges of PHP Email Validation

Despite their availability, these native PHP functions and libraries present several practical limitations. Their design choices often create a trade-off between simplicity, accuracy, and the ability to handle modern email standards.

• The filter_var() function struggles with RFC 5322 rules. It incorrectly handles quoted local parts and nested comments. This results in false negatives for valid addresses and false positives for malformed ones, a known issue in benchmarks.
• The filter_var() function is ASCII-centric and rejects Unicode characters, which makes it fail legitimate international addresses. The idn_to_ascii approach only converts the domain, so it still rejects UTF-8 characters in the local part of an email.
• A successful syntax check does not equal deliverability. The filter_var() function approves addresses with typos like user@gmailcom. This requires an extra checkdnsrr lookup, which adds latency and can be blocked in some sandboxed environments.
• The filter_var() function has rigid, hard-coded policies. It forbids dotless domains yet fails on valid edge cases like quoted addresses. Any extension requires custom wrappers with regex and DNS checks, which adds complexity to the validation logic.