I am trying to figure how to configure Postfix to operate within the requirements given by Spamhaus for free usage of their DNSBLs (http://www.spamhaus.org/organization/dnsblusage/). They specify that your use must be non-commercial (okay, that one is easy), you must not have more than 100,000 SMTP connections per day, and you must not have more than 300,000 queries to their DNSBLs per day.
So, I have been focusing on requirement number two, regarding the 100,000 maximum SMTP connections per day. Is there some way to make sure this is not exceeded in Postfix?
I was looking for a way to limit the total number of connections from any and all SMTP clients in a given time period. It seem that most of the rate or count limit options for smtpd that postfix has are in regard to the connections from a single client (http://www.postfix.org/TUNING_README.html#conn_limit). So, lowering these might help some, but it would not limit the total number of clients connecting within a time period.
Is there some way to limit the total number of clients connecting within a time period (so that I could control the maximum potential requests to the Spamhaus DNSBLs)?
Or, would this not be a good idea, because spam servers could fill the connection limit and real messages could never get through?
And, so would it then be better to just limit the connections per client like the postfix link shows?
Or, is there some other great way to help ensure you stay within the Spamhaus free use limits?