Two additional configuration options may be useful in some circumstances. The conn_throttle.so shared library also had a throttle_p function that would penalize connections that exceeded the limit by applying a consequence for an extended period beyond the basic 60 seconds. This same behavior is available in MeterMaid by configuring the following option on the MeterMaid server system:
configutil -o metermaid.table.ext_throttle.options -v penalize
This changes the behavior for the ext_throttle table so that connections may be penalized for connection attempts greater than the value set for metermaid.table.ext_throttle.quota.
The other option is relevant for systems that receive a large number of connections. Because MeterMaid is able to keep track of connections throughout the distributed MTA environment, it's possible that the limit of the number of connections being retained in MeterMaid's internal in-memory database may be insufficient for the overall volume of the MTA environment. The default is 1000 entries per table, but if you anticipate having more than 1000 connections per minute throughout your MTA environment, you can increase this number through this configuration option:
configutil -o metermaid.table.ext_throttle.max_entries -v max_entries
Note that even if the max_entries is reached during the 60 second period, MeterMaid will automatically discard the oldest and least frequently used entries. Thus, the more frequently connecting systems will remain in MeterMaid's table to be counted, keeping enough information to provide effective throttling.