it is basically the same jail as suggested in the forum which I linked above...
enabled = true
port = smtp,ssmtp,submission
protocol = tcp
filter = maxou-smtp-statistics
logpath = /var/log/maillog*
maxretry = 2
failregex = max connection rate 1/60s for \(smtp:<HOST>.*
it works great but definitely is much much too strong/restrictive... even if I increase the maxrentry value...