How to setup an smtp server on a UNIX machine !!!

Linux and Unix-Like Fedora
1

How to setup an smtp server on a unix-based machine. For example ubuntu, mac os x, fedora.

2

redhat.com | How to set up a home email server

3

have you considred usig google first? my first hit for "setup smtp ubuntu" is this:
Antonie Potgieter - Installing an SMTP server on Linux (Ubuntu)

4

Choose one of sendmail, postfix, exim, qmail.

5

Thanks for all the replies. This is what I want to do:

1.) I have two servers. Server 1 runs ubuntu and Server 2 runs mac os x 10.4
2.) postfix is already setup on Server 2
3.) I want to setup up smtp server on Server 1 for which, I am assuming I have to install post-fix as per DukeNuke2's instructions.
4.) Now, I want Server 1 to send out emails to Server 2 and Server 2 will send those emails to the outer world.

How can I do this ?