public function synchronize($varValue, $objUser, $objModule=null)
	{
		// Return if there is no user (e.g. upon registration)
		if ($objUser === null)
		{
			return $varValue;
		}

		$blnIsFrontend = true;

		// If called from the back end, the second argument is a DataContainer object
		if ($objUser instanceof DataContainer)
		{
			$objUser = $this->Database->prepare("SELECT * FROM tl_member WHERE id=?")
									  ->limit(1)
									  ->execute($objUser->id);

			if ($objUser->numRows < 1)
			{
				return $varValue;
			}

			$blnIsFrontend = false;
		}

		// Nothing has changed or e-mail address is empty
		if ($varValue == $objUser->newsletter || $objUser->email == '')
		{
			return $varValue;
		}

		$time = time();
		$varValue = StringUtil::deserialize($varValue, true);

		// Get all channel IDs (thanks to Andreas Schempp)
		if ($blnIsFrontend && $objModule instanceof Module)
		{
			$arrChannel = StringUtil::deserialize($objModule->newsletters, true);
		}
		else
		{
			$arrChannel = $this->Database->query("SELECT id FROM tl_newsletter_channel")->fetchEach('id');
		}

		$arrDelete = array_values(array_diff($arrChannel, $varValue));

		// Delete existing recipients
		if (!empty($arrDelete) && \is_array($arrDelete))
		{
			$this->Database->prepare("DELETE FROM tl_newsletter_recipients WHERE pid IN(" . implode(',', array_map('\intval', $arrDelete)) . ") AND email=?")
						   ->execute($objUser->email);
		}

		// Add recipients
		foreach ($varValue as $intId)
		{
			$intId = (int) $intId;

			if ($intId < 1)
			{
				continue;
			}

			$objRecipient = $this->Database->prepare("SELECT COUNT(*) AS count FROM tl_newsletter_recipients WHERE pid=? AND email=?")
										   ->execute($intId, $objUser->email);

			if ($objRecipient->count < 1)
			{
				$this->Database->prepare("INSERT INTO tl_newsletter_recipients SET pid=?, tstamp=$time, email=?, active=?, addedOn=?")
							   ->execute($intId, $objUser->email, ($objUser->disable ? '' : 1), ($blnIsFrontend ? $time : ''));
			}
		}

		return serialize($varValue);
	}