We have a lot of incoming mail server/handlers configured. One of the projects has an old email they are trying to phase out and a new email address. When I put the new address, predictably, only mail sent to that address creates/comments. When I remove the address (so catch email address is blank) both emails create/comment tickets.
Why does this work? How does it know to creates tickets from those emails in the correct project? Would it break if there were another project with a blank catch address (not something I'm going to test)?