We use policyd on the intensivelly sending e-mail server. Amount of e-mails - 1M per day. We use only one rule - 100 e-mails from one recipient per time period.
In the exploitation process we see in log that quota counter maybe grow on by one. Also I see that 3-5 e-mail sending in one second - maximal precission on timestamp field, that quota counter dont increase. But sometimes he can revert to negative value.
This some buggy behaviour make many trouble for us.
I use this fix and test it in production some months. Inspecting log and monitoring graph show that we dramatically decrease situation when one recipient send e-mails above the quota - 200-300 and more. Because they had negative value on the quota counter or they dont grow.
Now I also testing additional fix with transaction begin and commit.
Now we have only some bugs in counter like this:
03:47:19 quota=6.24/100 (6.2%), last_update=1488847639.78458, pid=15310, 03:47:19 quota=7.24/100 (7.2%), last_update=1488847639.81541, pid=24140, 03:47:19 quota=8.24/100 (8.2%), last_update=1488847639.81785, pid=24165, <-- equally timestamp 03:47:19 quota=8.24/100 (8.2%), last_update=1488847639.81785, pid=24171, <-- from different pid