In my instances I couldn't figure out the right number for limiting connections. It got problematic when roadwarrior SMTP AUTH users were unable to connect reliably.
Is the specific problem you're looking to solve simply connection limits or is there a different situation that you want connection limits to solve? If may anticipate the answer as being the latter.... I keep the system from drowning from massive waves by using the loadcheck plugin. They can then take the plethora of connections but when spamd starts sucking cpu to service the connected MTAs, it will just fire back a soft error. I've had very good experiences from this approach as well as when I was running the tcpserver framework. If you are specifically looking to limit connections, I'm sorry but I have no solution. peter
