Sendmail is not well-suited for the home user with a dynamic IP dialup account. You can make it work, but it will be painful. I notice the normally vocal crowd of people advocating other MTAs is silent on this issue. Evolution is still a work in progress. I cannot get sendmail to run.
All mail is delivered through that central host.
A bare minimum of local processing is done. No local delivery is possible. The local machine's identity is obliterated. Most other Sendmail features are disabled. Turn this off, too.