CentOS - Sep 2012 - More about Postifx mail server configuration and all

I have done postfix mail server installation and all configuration ,
restriction and filters .What should I have to do more for my mail server
so it is full protect and working fine and fast. like : Milter and
spamassassin is necessary for my mail server .

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Thanks & Regards
Jitendra Jha
+91-7498370550