email servers

[ChadDavis]

Hello.

I'm pretty unfamiliar with email servers.  I need to install a server in my local network to use for development of another application.  I just need a mail server available for the application.  I read some of the online documentation and became a bit confused about what constitutes a server.   Postfix is on the system.  What does it do?  I don't think it has anything to do with my email client, correct?  My email client talks to my ISP's POP server for incoming mail, and my ISP's SMTP server for outgoing mail.  It seems like what I need is a SMTP server locally.  Is the postfix such a thing?  If not, what is an easy one to install.

Thanks,
Chad