WordPress at a glance
filter is not described

is_email filter-hook . WP 2.8.0

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.

Usage

add_filter( 'is_email', 'filter_function_name_4191', 10, 3 );
function filter_function_name_4191( $is_email, $email, $context ){
	// filter...

	return $is_email;
}
$is_email(true/false)
Whether the email address has passed the is_email() checks.
Default: false
$email(string)
The email address being checked.
$context(string)
Context under which the email was tested.

Where the hook is called

is_email()
is_email
wp-includes/formatting.php 2905
return apply_filters( 'is_email', false, $email, 'email_too_short' );
wp-includes/formatting.php 2911
return apply_filters( 'is_email', false, $email, 'email_no_at' );
wp-includes/formatting.php 2921
return apply_filters( 'is_email', false, $email, 'local_invalid_chars' );
wp-includes/formatting.php 2928
return apply_filters( 'is_email', false, $email, 'domain_period_sequence' );
wp-includes/formatting.php 2934
return apply_filters( 'is_email', false, $email, 'domain_period_limits' );
wp-includes/formatting.php 2943
return apply_filters( 'is_email', false, $email, 'domain_no_periods' );
wp-includes/formatting.php 2951
return apply_filters( 'is_email', false, $email, 'sub_hyphen_limits' );
wp-includes/formatting.php 2957
return apply_filters( 'is_email', false, $email, 'sub_invalid_chars' );
wp-includes/formatting.php 2963
return apply_filters( 'is_email', $email, $email, null );

Where the hook is used (in WP core)

Does not used.