MailingManager::checkOnBeforeChainSend

static function checkOnBeforeChainSend($letterId)
{
	$event = new MainEvent('sender', 'onBeforeChainSend', ['LETTER_ID' => $letterId]);
	$event->send();
	foreach ($event->getResults() as $eventResult)
	{
		if (
			$eventResult->getType() === MainEventResult::ERROR
			|| $eventResult->getParameters()
			&& isset($eventResult->getParameters()['ALLOW_SEND'])
			&& $eventResult->getParameters()['ALLOW_SEND'] === false
		)
		{
			return false;
		}
	}

	return true;
}