option 1: Check your SMTP server is setup correctly. If your broadband service provider requires you to use their SMTP server, use their settings, otherwise use the settings for your email service. Also check if they require authentication and enable it if they do.
option 2: Buy him an iPad - it's a way better experience than a crusty old iMac on OS 9. Then go back to option 1 as you'll probably still have to do all that.