CAllMailMessage::addDefferedDownload

static function addDefferedDownload($mailboxID, $ID): void
{
	BitrixMailInternalsMailEntityOptionsTable::add([
		'MAILBOX_ID' => $mailboxID,
		'ENTITY_TYPE' => 'MESSAGE',
		'ENTITY_ID' => $ID,
		'PROPERTY_NAME' => 'UNSYNC_BODY',
		'DATE_INSERT' => new BitrixMainTypeDateTime(),
		'VALUE' => 'Y',
	]);
}