March 11, 2013

Trying to configure sendmail in Debian

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, the server can send mail to with no problem.

We can't send mail to external addresses like or Here's an example of what I get in /var/log/mail.log

Mar 7 14:45:29 newton sm-mta[17159]: r27JjOw1017159: to=, ctladdr= (0/0), delay=00:00:05, xdelay=00:00:05, mailer=relay, pri=30455, [], dsn=5.7.1, stat=User unknown

Sometimes it says stat=Unable to relay and sometimes stat=Sent, but in every case the emails are never received.

Also, I get this:

root@newton:/etc/mail# sendmail -bv deliverable: mailer relay, host, user

Does that mean the 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!

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