title: SSL certificate not accepted
body: <p>I am quite new to running my own mail server but I feel like I did a good job setting it up. It receives mail fluently but sending mail causes some issues.</p>
  
  <pre><code>tail -f /var/log/mail.log
  SSL_accept error from 5354D677.cm-6-5d.dynamic.ziggo.nl
  </code></pre>
  
  <p>And:</p>
  
  <pre><code>openssl s_client -connect mail.challenge-all.com:587 -debug
  result: SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol:s23_clnt.c:749
  </code></pre>
  
  <p>Thunderbird mail client (on send mail) (translated freely from dutch to english):</p>
  
  <pre><code>Sending of the message failed. Message can not be sent via
  SMTP-server smtp.challenge-all.com for an unknown reason.
  </code></pre>
  
  <p>I would be quite willing to supply more information, if you guys would be so kind to assist this eager but green mail server owner/maintainer :-)</p>
  
  <p>Additional info edit:</p>
  
  <ul>
  <li>I am using a setup of postfix/dovecot with spamassassin and clamav</li>
  <li>I got my signed certs from startssl.com and <a href="https://www.startssl.com/" rel="nofollow">https://www.startssl.com/</a> did chain with their intermediate CA</li>
  </ul>