sendmail password smtps...
 

I wan't to have authentication on all outgoing mail via smtps, I created key ect, now I am first of all wonder if this ssl key is to encrypt message, and second of all how to create smtps password, so that my mail server can not be exploited so easily, but at the same time I have a little safty to tinker around with who can send out stuff ect. So basically I want to know how to password protect outgoing mail. Help as always with me is greatly appreciated.