This is such an obvious 'bug' that I wanted to run it past people to be sure that I'd not misunderstood something. This is with the development build. In mail, when one opens an IMAP folder and clicks on a message, the message should be displayed in the mail viewer/editor. Instead a message is displayed: "Could not open "SUBJECT REF NAME" with application "DA.pl" (Invalid Argument). Would you like to find some other suitable application? It is then possible to click on the [Find] button and choose Mail from the list that appears but it seems to me that the mail item should open in Mail when it is double-clicked. It seems blatantly obvious to me. Am I missing something ? Michael.