Receiving mail from Postfix server

[Joshua Lokken]

Hello.

I am playing with mail servers.  I have just read the docs at postfix.org,
googled *some* for help, and installed Postfix.  The postfix server is
on my intranet.  The configuration and setup of Postfix itself was not so
bad.  It's running, and [I believe, from the docs I've read] configured
adequately.  When I send mail from the postfix box, the username/domain
are rewritten properly, but I see:

connect to joloxbox.joshualokken.com [10.0.0.2]: connection refused.

The box in question (joloxbox) is running stock sendmail.  I have found
docs on how to set up sendmail as a server.  I would like to know where
to go for help on how to make sendmail "know" that I want it to listen
for smtp on port 25, and that butler.joshualokken.com (the Postfix server)
is where it will get its mail.  

sockstat on joloxbox shows sendmail listening on port 25.  I am confused.
Would someone offer some advice on config/docs?  Thank you all.

--
Joshua