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.
The patch adds the whitelist feature but that is not the only change needed.
Check this post - it has the answer you need: https://community.magento.com/t5/Security-Patches/SUPEE-6788-Developer-Toolbox/