Hello My topic would spark some people in the forum, but to effectively fight spam, this would be a good thing for everybody, once again, that's my opinion. For Me, the default config of ISPConfig (which I do not criticize) works for me for 1 year and then these problems to go go ... Why not you? Voila, my opinion Mz ...
You can use postscreen on a ispconfig server if you want to do that. The setup is not ispconfig specific.