I understand from the presentation that you can handle an incoming mail (e.g. to categorise it). What happens if the user changes the categorisation rules (in my mail extension) - will those changes only apply to new messages or is there a mechanism to re-apply the new configuration to all mail in the inbox?
Mail Extensions - from message to all mail
Your extension will only be called for new incoming messages to the inbox. There is currently no way to reprocess the existing messages in the user's inbox. Please feel free to file a feedback request asking for this functionality.