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is_email( string $email, bool $deprecated = false )

Verifies that an email is valid.

Description

Does not grok i18n domains. Not RFC compliant.

Parameters

$email

(string) (Required) Email address to verify.

$deprecated

(bool) (Optional) Deprecated.

Default value: false

Return

(string|false) Valid email address on success, false on failure.

More Information

Does not grok i18n domains. Not RFC compliant.

It does not correctly test for invalid characters. This code does not distinguish email such as [email protected]:

if ( ! preg_match('/^[a-z0-9-]+$/i', $sub ) ) {
/** This filter is documented in wp-includes/formatting.php */
return apply_filters( 'is_email', false, $email, 'sub_invalid_chars' );
}

Source

File: wp-includes/formatting.php

function is_email( $email, $deprecated = false ) {
	if ( ! empty( $deprecated ) ) {
		_deprecated_argument( __FUNCTION__, '3.0.0' );
	}

	// Test for the minimum length the email can be.
	if ( strlen( $email ) < 6 ) {
		/**
		 * Filters whether an email address is valid.
		 *
		 * This filter is evaluated under several different contexts, such as 'email_too_short',
		 * 'email_no_at', 'local_invalid_chars', 'domain_period_sequence', 'domain_period_limits',
		 * 'domain_no_periods', 'sub_hyphen_limits', 'sub_invalid_chars', or no specific context.
		 *
		 * @since 2.8.0
		 *
		 * @param string|false $is_email The email address if successfully passed the is_email() checks, false otherwise.
		 * @param string       $email    The email address being checked.
		 * @param string       $context  Context under which the email was tested.
		 */
		return apply_filters( 'is_email', false, $email, 'email_too_short' );
	}

	// Test for an @ character after the first position.
	if ( strpos( $email, '@', 1 ) === false ) {
		/** This filter is documented in wp-includes/formatting.php */
		return apply_filters( 'is_email', false, $email, 'email_no_at' );
	}

	// Split out the local and domain parts.
	list( $local, $domain ) = explode( '@', $email, 2 );

	// LOCAL PART
	// Test for invalid characters.
	if ( ! preg_match( '/^[a-zA-Z0-9!#$%&\'*+\/=?^_`{|}~\.-]+$/', $local ) ) {
		/** This filter is documented in wp-includes/formatting.php */
		return apply_filters( 'is_email', false, $email, 'local_invalid_chars' );
	}

	// DOMAIN PART
	// Test for sequences of periods.
	if ( preg_match( '/\.{2,}/', $domain ) ) {
		/** This filter is documented in wp-includes/formatting.php */
		return apply_filters( 'is_email', false, $email, 'domain_period_sequence' );
	}

	// Test for leading and trailing periods and whitespace.
	if ( trim( $domain, " \t\n\r\0\x0B." ) !== $domain ) {
		/** This filter is documented in wp-includes/formatting.php */
		return apply_filters( 'is_email', false, $email, 'domain_period_limits' );
	}

	// Split the domain into subs.
	$subs = explode( '.', $domain );

	// Assume the domain will have at least two subs.
	if ( 2 > count( $subs ) ) {
		/** This filter is documented in wp-includes/formatting.php */
		return apply_filters( 'is_email', false, $email, 'domain_no_periods' );
	}

	// Loop through each sub.
	foreach ( $subs as $sub ) {
		// Test for leading and trailing hyphens and whitespace.
		if ( trim( $sub, " \t\n\r\0\x0B-" ) !== $sub ) {
			/** This filter is documented in wp-includes/formatting.php */
			return apply_filters( 'is_email', false, $email, 'sub_hyphen_limits' );
		}

		// Test for invalid characters.
		if ( ! preg_match( '/^[a-z0-9-]+$/i', $sub ) ) {
			/** This filter is documented in wp-includes/formatting.php */
			return apply_filters( 'is_email', false, $email, 'sub_invalid_chars' );
		}
	}

	// Congratulations, your email made it!
	/** This filter is documented in wp-includes/formatting.php */
	return apply_filters( 'is_email', $email, $email, null );
}

Changelog

Version Description
0.71 Introduced.

© 2003–2019 WordPress Foundation
Licensed under the GNU GPLv2+ License.
https://developer.wordpress.org/reference/functions/is_email