Mail Server configuration to accept all incoming message but option to Send Outgoing to a specific set of users?

Question

Is there any Mail Server which can accept all incoming message to a user and to a outgoing message should be sent to a particular usernames not to other accounts .

Answer 1

yes. exim, sendmail, postfix, qmail... most commonly used MTA's on a linux box can be configured to restrict relaying as you have described above, and for all of the examples above, documentation on relay control is pretty good.