If you have a fixed IP with a good reputation then 95% of your email problems are solved. If you use a client (like the iphone email client), your setup is really simple (as in set it up once and forget about it). Providers will also try re-sending email if it doesn't reach you, so availability is not that big of a deal.
That being said, the major issue starting up is having that highly reputable ip/domain.
That being said, the major issue starting up is having that highly reputable ip/domain.