This plugin places a maximum limit on the number of unrecognized commands allowed before recognising that the connection is bad.
If the limit is reached the connecting client is sent an error message and immediately (and rudely - technically an RFC violation) disconnected.
This plugin should be listed near the bottom of
config/plugins so that it
runs after any plugins that use the unrecognized_command hook to implement
other SMTP verbs and extensions (such as the auth/* plugins), otherwise
commands valid for these plugins will be counted as unknown by this plugin.
Specifies the number of unrecognized commands to allow before disconnecting. Default: 10.