I'm trying to configure sendmail on our Debian Linux server to send mail, using our Exchange server as a relay. I'm a total noob at all of this.

We can send mails to internal addresses (for example, if our domain name is ourdomain.com, the server can send mail to [email]bob@ourdomain.com[/email]) with no problem.

We can't send mail to external addresses like [email]bob@gmail.com[/email] or [email]bob@hotmail.com[/email]. Here's an example of what I get in /var/log/mail.log

Mar 7 14:45:29 newton sm-mta[17159]: r27JjOw1017159: to=<user9999@gmail.com>, ctladdr=<root@newton.forrest> (0/0), delay=00:00:05, xdelay=00:00:05, mailer=relay, pri=30455, relay=webmail.ourdomain.ws. [xxx.xxx.xxx.xxx], dsn=5.7.1, [B]stat=User unknown[/B]

Also, I get this:

[CODE]root@newton:/etc/mail# sendmail -bv user9999@gmail.com

user9999@gmail.com... deliverable: mailer relay, host webmail.ourdomain.ws, user user9999@gmail.com[/CODE]

Does that mean the [email]user9999@gmail.com[/email] is unknown to newton, or unknown to Exchange?

Is there something in Exchange we need to configure?

I have no idea what to configure. Please help. Thanks!