Installing Postfix
 

I am installing Postfix for the first time on my home server and I would like to install and test locally since I don't have a domain.

Therefore, when I'm editing the main configuration file, what do I put down instead of a FQDM (Fully Qulified Domain Name)?

Re: Installing Postfix
 

Make one up.. just make sure your other machines on your network can translate its name to IP though.. if your going to be testing with more than one machine..

Also, when I open up the root's mail account, there are welcome messages from the Distro. Does that mean mail can be sent to users on my machine? I was installing postfix so that users can send mail to each other - is this the correct approach?

I do believe that they can sendmail to each other using sendmail too. Locally it works the same way with postfix I think. You get it going, give it a test by mail -s "test mail" usernamehere

Yes, by default in most cases with every distro, sendmail is running or is installed and Linux in other terms has built-in email for local users.. ;)