[mmorse]

I'd leave them on-extra insurance.
-i might set the time it checks for clamav updates higher-like 24hrs or something
-and just turn off any outside real time blacklists if you have any

zmprov gacf | grep zimbraMtaRestriction to see what RBLs are set.

I'm not talking about:
reject_invalid_hostname
reject_non_fqdn_hostname
reject_non_fqdn_sender

I'm talking about the outside spam list checks-which take the most time, resources, and bandwidth:
reject_rbl_client dnsbl.njabl.org
reject_rbl_client cbl.abuseat.org
reject_rbl_client bl.spamcop.net
reject_rbl_client dnsbl.sorbs.net
reject_rbl_client sbl.spamhaus.org
reject_rbl_client relays.mail-abuse.org