code: public static function changeSubscriptionStatus(FrontendTemplate $objTemplate)
  	{
  		if (strncmp(Input::get('token'), 'com-', 4) === 0)
  		{
  			/** @var OptIn $optIn */
  			$optIn = System::getContainer()->get('contao.opt-in');
  
  			// Find an unconfirmed token with only one related record
  			if ((!$optInToken = $optIn->find(Input::get('token'))) || !$optInToken->isValid() || \count($arrRelated = $optInToken->getRelatedRecords()) != 1 || key($arrRelated) != 'tl_comments_notify' || \count($arrIds = current($arrRelated)) != 1 || (!$objNotify = CommentsNotifyModel::findByPk($arrIds[0])))
  			{
  				$objTemplate->confirm = $GLOBALS['TL_LANG']['MSC']['invalidToken'];
  
  				return;
  			}
  
  			if ($optInToken->isConfirmed())
  			{
  				$objTemplate->confirm = $GLOBALS['TL_LANG']['MSC']['tokenConfirmed'];
  
  				return;
  			}
  
  			if ($optInToken->getEmail() != $objNotify->email)
  			{
  				$objTemplate->confirm = $GLOBALS['TL_LANG']['MSC']['tokenEmailMismatch'];
  
  				return;
  			}
  
  			$objNotify->active = '1';
  			$objNotify->save();
  
  			$optInToken->confirm();
  
  			$objTemplate->confirm = $GLOBALS['TL_LANG']['MSC']['com_optInConfirm'];
  		}
  		elseif (strncmp(Input::get('token'), 'cor-', 4) === 0)
  		{
  			$objNotify = CommentsNotifyModel::findOneByTokenRemove(Input::get('token'));
  
  			if ($objNotify === null)
  			{
  				$objTemplate->confirm = $GLOBALS['TL_LANG']['MSC']['invalidToken'];
  
  				return;
  			}
  
  			$objNotify->delete();
  			$objTemplate->confirm = $GLOBALS['TL_LANG']['MSC']['com_optInCancel'];
  		}
  	}
docs: Change the subscription status
  
  @param FrontendTemplate $objTemplate