I need to set up an email server for my system and need some recommendations.

My system is RedHat 9 sitting behind a linksys firewall connected to a cable modem. I have a registered domain name which I will point to this system. I can map the ports where appropriate.

I want to be able to have several of us access mail sent to this domain, as well as the ability to send mail using this mail server while physically located anywhere on the internet. I also want to prevent unauthorized mail from being sent from this email server.

What software packages are appropriate for these tasks?

Thanks,

-KS