I used to use a catchall account on a domain to filter unwanted commercial mail: when I sign up on a site I use a unique email address, and when spam starts coming in on that email address I set it to bounce and report the muppet that sold my address to the data protection commissioner. I can't do that on Zimbra because it doesn't support bouncing, and I can't blackhole the junk because
the junk filters work before the user filters. So I created a catchall account to feed the spammy addresses into and discard everything above 0 bytes. Unfortunately, because of the problem mentioned above, the majority of the mail goes into the Junk folder, which has to be manually deleted.
I really shouldn't have had to type all that...
adam