/* Create custom message for new users */
function custom_email_for_news_user( $wp_new_user_notification_email, $user, $blogname ) {
	$key = get_password_reset_key( $user );

	/* translators: %s: User login. */
	$custom_message  = sprintf( __( 'Username: %s' ), $user->user_login ) . "\r\n\r\n";
	$custom_message .= __( 'To set your password, visit the following address:' ) . "\r\n\r\n";
	$custom_message .= network_site_url( "wp-login.php?action=rp&key=$key&login=" . rawurlencode( $user->user_login ), 'login' ) . "\r\n\r\n";

	$custom_message .= home_url() . "\r\n";

	$wp_new_user_notification_email['message'] = $custom_message;

	return $wp_new_user_notification_email;
}
add_filter( 'wp_new_user_notification_email', 'custom_email_for_news_user', 99, 3 );