I am completely new to Linux! So new I do not own a copy which is where you kind Linux people can help.

What I want to do is get experience in building and running a Linux mail server. As I do not have a Linux pacakge which one should I buy.

Do all Linux packages come with intergrated mail server software if not what extras will I require.

Are there any Licence issues I need to be aware of

Is there anything available on the public domain.

This will not be a permanent system and I will be taking it down and re-installing to get the practice and experience that I think I need.

Thanks in anticipation of you help.

Not a dumbo! Do some research! Here's a link to get you started: DistroWatch

Good luck to you!

...well that wasn't completely new!

I really like Gentoo Linux now that I have it running and it's auto-update and installware (Portage) is considered by many to be the best of its kind. (I think it only comes with Gentoo).
It compiles files on your own machine so that the software is rebuilt from scratch to be customized especially for your own system as you add and upgrade. The fact that recompiling takes longer is compensated for by the automated management system that checks for dependencies and makes sure everything is installed and in the right order.

But I don't know about its server-qualities...you can go to the Gentoo website to find out about that.

I would like you to try with Ubuntu which is a very clean distro. Moreover you have a GUI based tool for installing new programs.
I have been using it for our server for a last couple of months

-Prasanta.