Zimbra - How to Stop Automatically Discarding Spam

By default Zimbra automatically discards inbound mail that receives a high spam score (aka "super spam").  Although the score is configurable up to 100, this default could cause false positive email to disappear and make troubleshooting spam scoring difficult.

Change the default behavior using these commands:
su - zimbra
zmprov mcf zimbraAmavisFinalSpamDestiny D_PASS
zmprov ms <mta server> zimbraAmavisFinalSpamDestiny D_PASS
zmcontrol restart

Choose from these values:
D_PASS -> Deliver all spam regardless of score
D_BOUNCE -> Generate a bounce message
D_REJECT -> Reject the message
D_DISCARD -> Silently discard the message (default)