I've been an administrator of a postfix/amavisd-new/spamassassin setup for years so I'm very aware of how little spam is caught under a default install of these programs. I'm *assuming* that Zimbra, since it's based off of these core technologies, would have a similar dismal spam blocking ratio (no offense to Zimbra, I love the program). I'm looking at porting over my existing spamassassin config + razor2 + DCC + a few RBL's + whitelist/blacklist to a Zimbra installation. My only concern is the fact that several places (Improving Anti-spam system - Zimbra :: Wiki & Upgrade to 4.5.9 still breaks spam databases for an older version) mention that upgrades have the potential of wiping out the custom spam fighting rules when updating, even from one minor version to the next. I would like to hear from users with a similar, customized spam system on the pitfalls, workarounds, and tips for making the Zimbra upgrade process easier and more manageable. Thanks in advance.