Re: Do you host your own mail server at home?
I've had a mailserver at home for nearly a year. I use it for testing website features before they go live on the hosting site, and for getting system notifications.
It's set up to work only on the LAN, which is behind a NAT router. In addition, I've set up iptables on the relevant box, though I'm not sure it's actually doing anything that the router isn't. I've never seen any indication of unauthorised access.
Please, people, remember to BACKUP before you install that new system. Same if you're upgrading.