According to this wiki, Zimbra 8.0.6 should have accounting support within policyd.

Postfix Policyd - Zimbra :: Wiki

Our version is 8.0.6 and we don't seem to have accounting within the database. Does anyone have any idea why or possibly how we could add it in.

[zimbra@webmail ~]$ zmcontrol version
Release 8.0.6_GA_5922.RHEL6_64_20131203103705 RHEL6_64 FOSS edition.

sqlite> .tables
access_control greylisting_whitelist
checkhelo policies
checkhelo_blacklist policy_group_members
checkhelo_tracking policy_groups
checkhelo_whitelist policy_members
checkspf quotas
greylisting quotas_limits
greylisting_autoblacklist quotas_tracking
greylisting_autowhitelist session_tracking
greylisting_tracking