postfix security configuration

hi, my config: debian stable 3.0r1 postfix qpopper I have a small problem: my smtp after pop3 configuration works fine, no open relay possible, but the authentificated users can fake their own e-mail address. How can I stop it, so they can only use the adress which were set up for them. th

postfix security configuration

hi, my config: debian stable 3.0r1 postfix qpopper I have a small problem: my smtp after pop3 configuration works fine, no open relay possible, but the authentificated users can fake their own e-mail address. How can I stop it, so they can only use the adress which were set up for them.