My original problem is :
------------------------
	My company already exist a centralize email machine. What I 
	want is set up a mail server for my department. I already 
	install sendmail v8.8.5 (Solaris 2.5.1)
	
	Requirement :
	---------------------
	A) One main mail server, "mydepartment", 
	Other machine set as null client.
	B) If the "TO" user not belong to my department, mail
	system forward those email to company email
	server "companymail".
	C) user receive email send by my department staff
	From : userA	->	From : userA 	(No Change)
	D) other department staff receive email send by my department staff
	From : user A	->	From : userA@mydepartment
	E) outsides receive email send by  my department staff
	From : userA	->	From : userA@mydepartment.domain.com
	M4 macro for my department mail server :
	----------------------------------------
	include(`../m4/cf.m4')
	VERSIONID(`mydepartment.mc  Man Wu 4 June 1997')
	OSTYPE(solaris2)dnl
	MAILER(local)dnl
	MAILER(smtp)dnl
	I can deliver the email, when I send to other department (Requirement D),
	From : userA	->	From : userA@mydepartment.domain.com
	My question :
	-------------
	Q1) How to configure in order to meet my requirement
	Q2) During my testing, for undeliver email will send to postmaster with
	    body of messages, how can I delete the body due to privacy
	Q3) What is the different between "MAIL HUB" and "SMART HOST"
	04) If I define the userdb like this
		
		userdb file:
		------------
		userA		Man_Wu_userA
			
		The outgoing will be rewritten as "Man_Wu_userA", if someone send
		the email to "Man_Wu_userA@mydepartment.domain.com", Is userA
		receive this email ??
	05) What is the priority between alias (on NIS+) and userdb,
	
		Alisas file (on matter on files or NISplus)	    
		-----------
		userA:userB
		User db
		-------
		userA		Man_Wu_userA
Suggestion from Rich Pieri :
----------------------------
You should get "the bat book" (sendmail) from O'Reilly & Associates, by
Eric Allman and others.  It is the canonical reference for sendmail, and
you should have it if you are doing anything "funky" with your sendmail.cf.
Result :
--------
	So far, I am study "bat book", and not solve any question yet ..