What do you wish to achieve ? as the original post was from 2008.
I'd like users to be able to contribute to a whitelist by adding addresses to their contact list
You will need to follow Improving Anti-spam system - Zimbra :: Wiki first to enable whitelisting. Have you tried the script ?
I tried on a test box that was upgraded from 5.0.18 to 6.0.4 without success.
ERROR: account.NO_SUCH_ACCOUNT (no such account: gact)
Thought I would ask before I broke it...
ACC=`/opt/zimbra/bin/zmprov -l gaa`
Works same as on 4.0x versions.