My postfix master.cf has

127.0.0.1:10024 inet n n n - 30 spawn
user=filter argv=/usr/local/bin/smtpscanner

However, it never spawn more than 20 instances, no matter how heavy the incoming mail (SPAMs) or how large my active queue. It seems to be the bottleneck when email heavy traffic.

There is unlimited smtpd before the kav and virtually unlimited amavisd down line pipe.

Is 20 instances a restriction on Kav 5.0.5 on postfix ?

If so, can I simply download the version 6 and re-install my same license key for 5.0.5 ?

Thanks.