Can someone point me to a good newb' explanation on mail servers ?

I would like to send and receive mail directly from my own pc, (standalone)
But m not sure if im able to or what i need to install ?

Do i have to buy a domain name for instance ?

Will I need to leave my pc connected to the net at all times ?

If I was to switch off or lose my connection for a period of time what would happen say if someone was sending me a e-mail and i wasnt connected ?

Im a little confused

This is very superficial, you'd better look for a howto on www.tldp.org about mail servers. what I know is:

- To send email you need one daemon, to receive is another one different. Sending requires smtp. Receiving requires pop3.

- To send email, you can just start the server when you need. To receive email, you'd better be online all the time.

- If a machine tries to send email to you and fails, it will try another more times, until it gives up. These timeouts depend on every sysadmin. If the whole process fails, you won't receive that email.

- Keeping a pop3 daemon is a more serious thing, as it relies on a kinda "24/7" hardware.
- Keeping a sendmail server is also a serious thing, because you can be acting as a mail relay to spammers, if misconfigured. Be very careful and study deeply the issue.

- Keeping a sendmail daemon online ONLY when you need to send mail is a more feasible thing. But even so, there are security issues.

You could setup a dynamic domain name (i.e. http://www.dyndns.org) for free if you want to try it out first. There are quite a few companies that provide such a service. Do a search on google if you want to see more companies.