as i can see this project is what i was looking for but freebsd is not listed in supported systems. what can be done for it to be supported?
It should be possible to use ISPConfig on FreeBSD. Earlier versions of ISPConfig were running on FreeBSD 5.0 and 5.1. If you adjust the files setup, dist.txt and the files in the mod directory (all in the directory install_ispconfig, after you unpacked ISPConfig), it might be possible that ISPConfig works on FreeBSD, but I haven't tested. If this works, please tell me, and I give you instructions how to compile a new SpamAssassin (the one that comes with ISPConfig was compiled on Linux, so it has to be replaced).