title: how to avoid email header Received: from unknown and email going to spam
body: <p>I try to send email from our server using php and Zend_Mail. I use smtp transport. This is confimation email of subscribing. But for some reason email that I send has strange headers and email goes to spam folder (I see them in gmail that receive letter):</p>
  
  <pre><code> Message-Id: &lt;50ee94f7.84fc440a.62dc.ffff9685SMTPIN_ADDED_MISSING@mx.google.com&gt;
      Received: (qmail 10943 invoked from network); 10 Jan 2013 10:16:22 -0000
      Received: from unknown (HELO searchboxindustries.com)  (username@searchboxindustries.com@207.162.215.30)
  </code></pre>
  
  <p>What does it mean list header "Recieved: from unknown"? Can it make email go to spam? How to avoid this strange header and make email avoid spam folder? Is there any problem with coode or maybe I have some problems with DNS settings of this domain? </p>
  
  <p>Here's code for setting headers:</p>
  
  <pre><code>$mailer-&gt;setFrom($params['list_email'], $params['list_from_name']);
  $mailer-&gt;setReplyTo($params['list_email']);
  
  $mailer-&gt;addHeader('Sender', $params['list_email'] . '.searchboxindustries.com');                       
  $mailer-&gt;setReturnPath($params['list_email'] . '.searchboxindustries.com');         
  
  $mailer-&gt;addTo($params['email_address']);
  </code></pre>
  
  <p>Code to configure transport:</p>
  
  <pre><code>$emailConfig = $this-&gt;getOption('email');                                   
          $transport = new Zend_Mail_Transport_Smtp($emailConfig['server'], $emailConfig);
  Zend_Mail::setDefaultTransport($transport);
  </code></pre>
  
  <p>Email config from application.ini:</p>
  
  <pre><code>   email.name  = searchboxindustries.com
     email.server = searchboxindustries.com
     email.username = user_name
     email.password = password
     email.auth = plain
     email.port = 587
  </code></pre>
  
  <p>Here are headers of such email:                                          </p>
  
  <pre><code>Delivered-To: gala19612009@gmail.com
  Received: by 10.76.94.204 with SMTP id de12csp111150oab;
          Fri, 11 Jan 2013 01:58:49 -0800 (PST)
  X-Received: by 10.69.0.8 with SMTP id au8mr228881813pbd.58.1357898329423;
          Fri, 11 Jan 2013 01:58:49 -0800 (PST)
  Return-Path: &lt;opp@mail15.com.searchboxindustries.com&gt;
  Received: from smtp1-1.searchboxindustries.com (mta1.searchboxindustries.com. [207.162.215.30])
          by mx.google.com with SMTP id d7si4727205paw.95.2013.01.11.01.58.48;
          Fri, 11 Jan 2013 01:58:48 -0800 (PST)
  Received-SPF: pass (google.com: domain of opp@mail15.com.searchboxindustries.com designates 207.162.215.30 as permitted sender) client-ip=207.162.215.30;
  Authentication-Results: mx.google.com;
         spf=pass (google.com: domain of opp@mail15.com.searchboxindustries.com designates 207.162.215.30 as permitted sender) smtp.mail=opp@mail15.com.searchboxindustries.com
  Message-Id: &lt;50efe258.a74b420a.3351.12fcSMTPIN_ADDED_MISSING@mx.google.com&gt;
  Received: (qmail 21583 invoked from network); 11 Jan 2013 09:58:48 -0000
  Received: from unknown (HELO searchboxindustries.com) (username@searchboxindustries.com@207.162.215.30)
    by searchboxindustries.com with SMTP; 11 Jan 2013 09:58:48 -0000
  From: Oleg &lt;opp@mail15.com&gt;
  Reply-To: opp@mail15.com
  Sender: opp@mail15.com.searchboxindustries.com
  Return-Path: opp@mail15.com.searchboxindustries.com
  To: gala19612009@gmail.com
  Subject: List1: Confirm Subscription
  Date: Fri, 11 Jan 2013 04:58:48 -0500
  Content-Type: text/html; charset=utf-8
  Content-Transfer-Encoding: quoted-printable
  Content-Disposition: inline
  MIME-Version: 1.0
  </code></pre>
  
  <p>Spf seems to be ok.
  The ip from which email is sent is not blacklisted. </p>
  
  <p>Now there are changes in DNS and I have headers:</p>
  
  <pre><code>Message-Id: &lt;50f41c80.67e3440a.2d32.6aabSMTPIN_ADDED_MISSING@mx.google.com&gt;
  Received: (qmail 18457 invoked from network); 14 Jan 2013 14:55:59 -0000
  Received: from unknown (HELO smtp1-1.searchboxindustries.com) (username@searchboxindustries.com@207.162.215.30)
    by searchboxindustries.com with SMTP; 14 Jan 2013 14:55:59 -0000
  </code></pre>
  
  <p>We have Reverse DNS set. 207.162.215.30 is resolved to stmp1.searchboxindustries.com. What's the problem then? I wonder what is strange format in brackets in the header Received : from unknow:</p>
  
  <pre><code> username@searchboxindustries.com@207.162.215.30
  </code></pre>