We have to have a catchall email account because we have a lot of different [email protected] addresses out there that people use (for better or for worse!), not to mention people who screw up email addresses with important emails.
But we do not have an edge transport server.
My understanding is that to set up a catchall account, you have to create a new email account, disable recipient filtering on the edge transport server, and then create a rule on the edge transport server to copy (or redirect) messages to the catch-all mailbox.
I assume that without an edge transport server, that filtering isn’t happening at all (but that’s just a guess) but even so we still need to do the redirecting.