If I drag a mail item from Airmail to BusyCal, I get TWO events created. One has a subject that is the same as the mail message, and a File attachment that is a blue link, but does nothing when I click it. The second appointment is labeled "Untitled", but has a URL: Open in Airmail, which works when I click it. The Untitled appointment is most useful, because it contains a working link to the item in Airmail. The other appointment is of no value, because although the subject is the same as the mail message, the link doesn't do anything. Having a single appointment with the correct subject and a working link would be the correct fix.