I know you can use rules to filter messages in the Mail App, I am having a bit of trouble applying the rules to existing messages in the inbox, I have around 600 messages and would like to delete multiples / create a filter I know it works for subsequent messages but what about messages in the mail app now? for example when you create a filter in Gmail it gives you the option to apply the filter for matching conversations,I dont see that in this app, I also do not see an option to select all, empty trash , only erase deleted items, sorry for the long post hopefully it made sense , I'm on Mountain Lion btw