This plugin will stop Haraka accepting new connections when the event loop latency is too high.
See node-toobusy for details.
To use this plugin you have to install the 'toobusy-js' module by running 'npm install toobusy-js' in your Haraka configuration directory.
This plugin should be listed at the top of your config/plugins file so that it runs before any other plugin that hooks lookup_rdns.
If you wish to override the default maxLag value of 70ms then add the desired value to config/toobusy.maxlag. This can be set and changed at runtime and no restart is required.
Note that if you set the maxLag value to <10 then this will cause the toobusy module to raise an exception which will cause Haraka to stop.