Do NOT host at home.

For one, this violates every second provider's ToS, if not every single one.

For two, lots of providers block incoming SMTP connections on TCP/25. More importantly, they may start blocking it without notice and you'll have no clue that they did.

For three, you will most likely end up on a RBL (blacklist) in no time solely because you come from a "consumer" IP range.

I mean, hosting at home is technically simple, but in the end it created more problems that it solves. Get a hosted server and use it instead.