Sendmail: Refusing Connections, and authentication/relaying

[Veritas]

Two prime issues for me on this one.

First, and most crucial: sendmail seems to be set up and working fine; I can 
send mail from the local machine to other hosts.

However, I haven't been able to convince it to accept SMTP connections from 
other hosts. cyrus-imapd seems to be set up and running fine, but the smtp 
port is, according to a friend, filtered and unavailable. I've been trying to 
scan through the sendmail configuration readme as well as the FreeBSD 
handbook, and will continue looking, but as of this time I haven't found a 
way to open it up to outside connections. FreeBSD 5.1, sendmail 8.12.9, no 
firewall presently running.

Once I can get sendmail accepting connections, it brings me to point B: Is it 
possible to set up sendmail so that local users can send to wherever, but 
remote users have to authenticate to do so(and can basically use my server as 
a remote mail host)? I don't want to run sendmail promiscuously, but it would 
be very nice if I could convince it to allow authenticated remote users to 
send to anywhere.

Or am I confused on the definition of "relay"? If it doesn't apply to people 
who use authentication, I'm already fine, and can just work on setting up 
secure auth.

-BB