Flood
From Scriptwiki
This command allows you to turn flood protection on or off and to change the above settings.
/flood [+c|-c] [on|off|clear] <bytes> <maxlines> <maxmessages> <ignoretime>
Typing /flood with no parameters gives you the current flood status.
You can type /flood on to turn flood protection on with the default settings.
You can also use +c or -c to enable or disable the ctcp flood protection.
Example
/flood 200 10 2 30
Here mIRC will check for flooding if it has sent 200 or more characters to the server, will buffer a maximum of 10 lines and ignore the rest, will only allow each user 2 buffered lines, and will ignore a user for 30 seconds if that user exceeded the maximum number of buffered messages.