I see it is available in ISP Config, but the values are all 0. How can I go about enabling this feature as I have a lot of clients using just mail and I am wanting to keep track of the data usage. TIA
Disabling Rspamd will not help you to solve the issue, as Rspamd is not the cause. The reason that you do not have this kind of log is that Rspamd can not write it. You could switch to an older spam filter, Amavisd. Then you have this kind of log but worse spam filtering results. Also, we will probably remove Amavisd in the future as we have not supported it on recent systems for several years now, so your system will not be upgradable.