Hi People

I am running Posfix 1.11 version; I have defined several aliases, certain users using them as distribution list ,all is o.k; problem arise when I want to enforce 'POLICY' regrading these aliases;thats mean - only certain,predifend
users (accounts) will have the ability to send mail thru these aliases, the others - just to read the mail.
What should I do to define and enforce such a "alias policy" ?