There is a warning shown to administrators when creating users that would replicate too many docs either via the admin app or cht-conf. However I suspect this warning doesn’t show when moving contacts. That would be a useful addition to cht-conf.
After the fact, these misconfigured users can be detected using the APIs created in this issue.
It would be possible to block replication completely when the user is over the limit, but I worry that be jarring for existing users that create one more doc and suddenly are blocked from replication. One compromise would be to have a warning limit as well as a higher limit that blocks the user completely, so there’s time for the admin to fix the replication/purging settings before the user is cut off.
Another issue is the user is only shown the warning the first time they log in, so a user who has been misconfigured will not see the warning at all.
Do you know how far over the limit the users were?