I'd like to customize the Undelivered Mail message

[guises]

I need to change the Undelivered Mail message so that I can identify the source of the original email using a filter. As it stands, since everything is put into an attachment, none of Zimbra's filters can read that.

How can I do this? I'm assuming that there's a configuration file somewhere. Feel free to set me straight.

[guises]

Nothin' from nobody? This has to be possible. Maybe I could kill a goat? And hang its carcass from the server rack? I don't know, I'm just brainstorming.