function SendDailyReportAgent() {
    global $DB;

    $email = 'sekrylov@gmail.com, grg767@yandex.ru';
    $eventName = "DAILY_REPORT_STATS";
    
    // Определяем даты для названия файла
    $dateStart = date('d-m-Y', strtotime("-30 days"));
    $dateEnd = date('d-m-Y');
    $fileName = "puhovik_statistics_{$dateStart}_{$dateEnd}.xls";

    $subject = "Ежедневный отчет по активности ($dateEnd)";

    $DB->Query("SET @DateT = ADDDATE(CURDATE(), INTERVAL -30 DAY)");

    $sql = "
    SELECT 
        IFNULL(CAST(Date AS CHAR), 'ИТОГО') AS 'DATE_VAL',
        SUM(TotalSessions) AS SESSIONS,
        SUM(TotalUsersRegistration) AS REG_TOTAL,
        SUM(UsersWithBirthdate) AS WITH_BDAY,
        IF(SUM(TotalUsersRegistration) > 0, ROUND(SUM(UsersWithBirthdate) / SUM(TotalUsersRegistration) * 100, 2), 0) AS KOEF_BDAY,
        SUM(UsersWithEmail) AS WITH_EMAIL,
        IF(SUM(TotalUsersRegistration) > 0, ROUND(SUM(UsersWithEmail) / SUM(TotalUsersRegistration) * 100, 2), 0) AS KOEF_EMAIL,
        SUM(TotalOrder) AS ORDERS,
        SUM(CountReserves) AS RESERVES,
        SUM(CountPickup) - SUM(CountReserves) AS PICKUP,
        SUM(CountPartners) AS PARTNERS,
        SUM(AddToCart) AS ADD_CART,
        SUM(CartToOrder) AS ORDER_FROM_CART,
        IF(SUM(AddToCart) > 0, ROUND(SUM(CartToOrder) / SUM(AddToCart) * 100, 2), 0) AS KOEF_ORDER
    FROM (
        SELECT DATE(`DATE_REGISTER`) AS Date, COUNT(`ID`) AS TotalUsersRegistration, COUNT(`PERSONAL_BIRTHDAY`) AS UsersWithBirthdate, COUNT(`EMAIL`) AS UsersWithEmail, 0 AS TotalOrder, 0 AS CountReserves, 0 AS CountPickup, 0 AS CountPartners, 0 AS TotalSessions, 0 AS AddToCart, 0 AS CartToOrder FROM `b_user` WHERE `DATE_REGISTER` >= @DateT GROUP BY Date
        UNION ALL
        SELECT DATE(a.DATE_INSERT) AS Date, 0, 0, 0, COUNT(DISTINCT a.ID), COUNT(DISTINCT prop.ORDER_ID), COUNT(DISTINCT dlv.ORDER_ID), COUNT(DISTINCT part.ORDER_ID), 0, 0, 0 
        FROM `b_sale_order` AS a
        LEFT JOIN `b_sale_order_props_value` AS prop ON a.ID = prop.ORDER_ID AND prop.ORDER_PROPS_ID = '22' AND prop.`VALUE` LIKE 'Y%'    
        LEFT JOIN `b_sale_order_delivery` AS dlv ON a.ID = dlv.ORDER_ID AND dlv.DELIVERY_ID = 76
        LEFT JOIN `b_sale_order_delivery` AS part ON a.ID = part.ORDER_ID AND part.DELIVERY_ID <> 76
        WHERE a.DATE_INSERT >= @DateT GROUP BY Date
        UNION ALL
        SELECT DATE(`TIMESTAMP_X`) AS Date, 0, 0, 0, 0, 0, 0, 0, COUNT(`SESSION_ID`), 0, 0 FROM `b_user_session` WHERE `TIMESTAMP_X` >= @DateT GROUP BY Date
        UNION ALL
        SELECT DATE(`DATE_INSERT`) AS Date, 0, 0, 0, 0, 0, 0, 0, 0, COUNT(DISTINCT `FUSER_ID`), COUNT(DISTINCT `ORDER_ID`) FROM `b_sale_basket` WHERE `DATE_INSERT` >= @DateT GROUP BY Date
    ) combined
    GROUP BY Date WITH ROLLUP;
    ";

    $res = $DB->Query($sql);

    // Шапка таблицы (общая для HTML письма и XLS)
    $tableHeader = '<tr style="background: #f4f4f4;">
                <th>Дата</th><th>Сессии</th><th>Зарег.</th><th>ДР</th><th>% ДР</th>
                <th>Email</th><th>% Email</th><th>Заказы</th><th>Резерв</th>
                <th>Самовывоз</th><th>Партнеры</th><th>В корзину</th><th>Из корзины</th><th>% Заказа</th>
              </tr>';

    $tableRows = '';
    while ($row = $res->Fetch()) {
        $isTotal = ($row['DATE_VAL'] === 'ИТОГО');
        $style = $isTotal ? ' style="font-weight:bold; background:#eee;"' : '';
        
        $tableRows .= "<tr$style>
                    <td>{$row['DATE_VAL']}</td>
                    <td>{$row['SESSIONS']}</td>
                    <td>{$row['REG_TOTAL']}</td>
                    <td>{$row['WITH_BDAY']}</td>
                    <td>{$row['KOEF_BDAY']}%</td>
                    <td>{$row['WITH_EMAIL']}</td>
                    <td>{$row['KOEF_EMAIL']}%</td>
                    <td>{$row['ORDERS']}</td>
                    <td>{$row['RESERVES']}</td>
                    <td>{$row['PICKUP']}</td>
                    <td>{$row['PARTNERS']}</td>
                    <td>{$row['ADD_CART']}</td>
                    <td>{$row['ORDER_FROM_CART']}</td>
                    <td>{$row['KOEF_ORDER']}%</td>
                  </tr>";
    }

    $html = '<h2 style="font-family: Arial;">Отчет за последние 30 дней</h2>';
    $html .= '<table border="1" cellpadding="5" cellspacing="0" style="border-collapse: collapse; font-family: Arial; font-size: 12px;">' . $tableHeader . $tableRows . '</table>';

    // Формируем контент для XLS (Excel понимает HTML таблицы, если указать кодировку)
    $xlsContent = '<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body>';
    $xlsContent .= '<table border="1">' . $tableHeader . $tableRows . '</table></body></html>';

    // Сохраняем временный файл для отправки
    $tempPath = \CTempFile::GetFileName($fileName);
    CheckDirPath($tempPath);
    file_put_contents($tempPath, $xlsContent);

    // Регистрируем файл в системе Битрикс
    $fileId = \CFile::SaveFile(
        array(
            "name" => $fileName,
            "size" => filesize($tempPath),
            "tmp_name" => $tempPath,
            "type" => "application/vnd.ms-excel",
            "MODULE_ID" => "main"
        ),
        "reports"
    );

    // Отправка письма
    \Bitrix\Main\Mail\Event::send(array(
        "EVENT_NAME" => $eventName,
        "LID" => "s1", 
        "C_FIELDS" => array(
            "EMAIL_TO" => $email,
            "SUBJECT"  => $subject,
            "MESSAGE"  => $html,
        ),
        "FILE" => array($fileId), // Добавляем ID файла во вложение
    ));

    // Опционально: удаляем файл из БД после постановки в очередь (Битрикс скопирует его в почтовую очередь)
    // \CFile::Delete($fileId); 

    return "SendDailyReportAgent();";
}
<pre>[RuntimeException] 
Could not start session because headers have already been sent. &quot;/data/www/bitrix/catalog_export/report_stat_send_email.php&quot;:1. (0)
/data/www/bitrix/modules/main/lib/session/session.php:143
#0: Bitrix\Main\Session\Session-&gt;start()
	/data/www/bitrix/modules/main/lib/session/kernelsessionproxy.php:47
#1: Bitrix\Main\Session\KernelSessionProxy-&gt;start()
	/data/www/bitrix/modules/main/include.php:182
#2: require_once(string)
	/data/www/bitrix/modules/main/include/prolog_before.php:19
#3: require_once(string)
	/data/www/bitrix/modules/main/include/prolog.php:10
#4: require_once(string)
	/data/www/bitrix/header.php:1
#5: require(string)
	/data/www/catalog/index.php:2
#6: include_once(string)
	/data/www/bitrix/modules/main/include/urlrewrite.php:128
#7: include_once(string)
	/data/www/bitrix/urlrewrite.php:2
----------
</pre>