WPForms: add BCC email header to notification emails

add_filter( 'wpforms_email_headers', function ( $headers, $emails ) {

	// APPLY THE BCC TO THIS FORM ID ONLY.

	// CHANGE THE ID TO THE FORM YOU NEED. OR REMOVE THE WHOLE IF BLOCK IF NEEDED FOR ALL FORMS.

	if ( 42 !== $emails->form_data['id'] ) {

		return $headers;

	}

	// CHANGE THIS EMAIL ADDRESS TO YOURS:

	$bcc_email = '[email protected]';

	$headers .= "Bcc: $bcc_email\r\n";

	return $headers;

}, 10, 2 );