after having initiated several actions to decrease spam-level, the results have been very positive.
Despit the increased number of Bot-drones on the Internet, the spam level has decreased considerable (more than 25%). The actions taken were notably:

• Instore Greylisting
• Configure Postfix to be very restrictive in SMTP-Header and enforce Communication protocol
• make the solsys.org domain a secret-registered domain - this to prevent everyone to see my details on request. They'll have to explicitely ask my registrar for my details - and I will be notified before these beeing sent out
• restrict access to all electronic addresses on my website

So - there is after all the possibility to lower the spam flooding after all...