Max Connections - Postfix

[DruKe]

I've searched and searched but couldn't find anything on this.
I want to make sure certain subnets can deliver ALL mail to our ISPconfig server, but still limit other mail servers.
A lot of our customers use a third party SPAM filtering service to clean the mail before even getting to our server. Needless to say, a lot of connections come from their subnets for delivery.
Is there a postfix directive to make sure that they NEVER get stopped?

Thanks!

[DruKe]

**bump**

[falko]

I don't know a solution.