Sendmail - problem sending to own domain when web host is not the mail host
I recently set up a web server using mydomain.com. I have a properly configured mail server for this domain that is hosted by a third party.
After installing sendmail, I can send messages to any domain but my own. The message I'm getting in the mail log is "user unknown" because sendmail is treating mail sent to mydomain.com as local mail. How do I get sendmail to treat messages sent from the web server to mydomain.com like any other message?