Do you guys have permanent connections or dial up? Static IP or dynamic? Here's a quick howto for your situation. What you have to do is go to the people who you bought the domain from (registrar) and find out if they will allow you modify your domain settings (IP pointing, Stealth redirection, MX settings etc etc). If they don't goto someone that will allow you to do this,
www.mydomain.com is a great one and it's free. If you chose
www.mydomain.com you will have to modify the DNS settings at your registrar to point to the
www.mydomain.com DNS servers. Once this is done you then setup an account with mydomain.com and add your domain(s) to this account. There are basically 2 types of service MyDomain and MyDNS. Make sure to setup your domain using MyDNS as there are heaps more options with this one and from there you can further setup your mail settings and subdomains. There is a whole range of options to chose from, you can have a catchall e-mail or redirect your e-mail to another e-mail address. Hope this helps out a bit.