title: Why is EXIM not able to verify sender?
body: <p>Puzzling problem sending emails from one server to another.</p>
  
  <p>Sending from <code>Server-01 pr@example.camp</code> TO <code>Server-02 eman@example.edu.au</code></p>
  
  <p>Server 02 bounces with <code>sender verify fail for &lt;pr@example.camp&gt;: Unrouteable address</code></p>
  
  <p>On Server-02 running <code>dig MX example.camp</code> resolves fine with:</p>
  
  <pre><code>;; ANSWER SECTION:
  mus.camp.               2869    IN      MX      10 server01-aus.emanwebdesign.com.
  mus.camp.               2869    IN      MX      0 server01-aus.emanwebdesign.com.
  
  ;; AUTHORITY SECTION:
  mus.camp.               2869    IN      NS      ns10.domaincontrol.com.
  mus.camp.               2869    IN      NS      ns09.domaincontrol.com.
  </code></pre>
  
  <p>Also from Server-02 I can telnet into port 25 of mus.camp and verify the existence of the email address (pr@...). </p>
  
  <p>Any clues as to why Exim's sender verify is failing?</p>
  
  <p><strong>Edit</strong>
  <code>exim -bvs pr@example.camp</code> returns</p>
  
  <p><code>pr@example.camp failed to verify: Unrouteable address</code></p>