Hi, blocks and variables need to be whitelisted now to be used in filters. I think that this is a very good thing. Problem is that I want to monitor what variables and blocks now fail to be parsed. The check is done high up in the tree in the function "blockdirective" in the Mage_Core_Email_Template_Filter. It is impossible to override it in a way that the descendants of this class also use the logging.
What is the best way to approach this because rather see my blocks failing to parse in a log than hearing it from the customers.