>Hi.. Jerry,
>
>I saw sendmail service was selected, is it possible for me to use this service only without install any additional software package like Ximian or something else as you told me? thanks

Sendmail acts only as an SMTP deamon and doesn't include higher level features of client packages like Exchange. That's why, if you want Exchange compatibility at the client level you need something like Evolution. Binari also produces a similar package but they are propriatary and cost $$$.
JLK