I have a system running RedHat 7.1, connected to the net over a Time-Warner cable modem. I get my IP address from TW's dhcp server, and it sometimes changes when I have to reboot. I am using dyndns.org and one of their little update clients to map the domain foobar.homeip.net (not the actual domain) to whatever actual ip address I have at the moment, and this works quite well. I can use ssh and sftp to get into my system remotely via this domain name.
I would like to be able to send mail to a personal account on this machine as well, but so far, I can't figure out how to set it up. I presume that I need to store the domain name somewhere on the local machine (/etc/hosts? /etc/defaultdomain? /etc/HOSTNAME?) I also need to set up sendmail.cf so it knows who it is and where to put incoming mail. All of the documentation I have seen so far assumes that you have a fixed ip address. Is there a step-by step guide somewhere to setting up this kind of a configuration, or can someone spell it out for me here?