Max Childern
How many MailScanner processes do you want to run at a time?
There is no point increasing this figure if your MailScanner server is happily keeping up with your mail traffic. If you are running on a server with more than 1 CPU, or you have a high mail load (and/or slow DNS lookups) then you should see better performance if you increase this figure.
As a rough guide, try 5 children per CPU.