First of all, I am very happy to participate in this community. We have installed Zimbra and we are surprised by how well it works. Of course there are some things which are a bit annoying. I would like to ask how to change the error messsage. Now, when the address is unknown the error: host mail.domain.tld [8x.xx.xx.xx]: 550 5.1.1 <something@domain.ltd>: Recipient address rejected: domain.tld.

We would like to receive a message like this: 550 "Unknown User" or something like that. When someone hits not existing mailbox on our server.

How to achieve this?

thank you so much.