title: Setup linux server to use Exchange server as relay
body: <p>It used to be working, but out of the blue, it stopped sending mail. I thought I set everything up in both linux and exchange to function correctly, but we're not receiving the emails - internally or externally.</p>
  
  <p>I'm not that knowledgeable about linux, so I use webmin to get around.</p>
  
  <p>So, we have our shopping cart and online forms on the linux server that will email users confirmations and such. It won't receive any mail, so I don't need to worry about that. It only sends mail out, both inside our network, and outside. Here is a recent addition to the mail log:</p>
  
  <pre><code>Dec  6 11:51:04 istalinux2 sendmail[1696]: rB6Gp4lr001696: from=www-data, size=246, class=0, nrcpts=1, msgid=, relay=www-data@localhost
  Dec  6 11:51:05 istalinux2 sm-mta[1697]: rB6Gp4hY001697: from=, size=485, class=0, nrcpts=1, msgid=, proto=ESMTP, daemon=MTA-v4, relay=localhost [127.0.0.1]
  Dec  6 11:51:05 istalinux2 sendmail[1696]: rB6Gp4lr001696: to="John Smith" jsmith@ista-in.org, ctladdr=www-data (33/33), delay=00:00:01, xdelay=00:00:01, mailer=relay, pri=30246, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (rB6Gp4hY001697 Message accepted for delivery)
  Dec  6 11:51:05 istalinux2 sm-mta[1699]: rB6Gp4hY001697: to=jsmith@ista-in.org, delay=00:00:01, xdelay=00:00:00, mailer=relay, pri=120485, relay=10.20.51.30, dsn=5.1.2, stat=Host unknown (Name server: 10.20.51.30: host not found)
  Dec  6 11:51:05 istalinux2 sm-mta[1699]: rB6Gp4hY001697: to=www-data@istalinux2.ista-in.org, delay=00:00:01, mailer=local, pri=120485, dsn=5.1.1, stat=User unknown
  Dec  6 11:51:05 istalinux2 sm-mta[1699]: rB6Gp4hY001697: rB6Gp5hY001699: postmaster notify: User unknown
  Dec  6 11:51:05 istalinux2 sm-mta[1699]: rB6Gp5hY001699: to=root, delay=00:00:00, xdelay=00:00:00, mailer=local, pri=30000, dsn=2.0.0, stat=Sent</code></pre>
  
  <p>I have a receive connector set up in Exchange to receive incoming mail from our linux server and pass it through.</p>
  
  <p>I am using sendmail in linux - but I honestly don't care how it's set up, as long as it works and doesn't break, lol. Please help me make sure all my settings in linux are correct ... and keep in mind that I am NOT a linux guy.</p>