title: How to break a postfix php filter if it is false
body: <p>I'm using postfix to recieve emails and send them through a php file for filtering.</p>
  
  <p>in de postfix master.cf i use:  </p>
  
  <pre><code>`smtp inet n - - - - smtpd -o content_filter=PHPFilter:dummy`  
  </code></pre>
  
  <p>or  </p>
  
  <pre><code>`pickup fifo n - - 60 1 pickup -o content_filter=PHPFilter:dummy`
  </code></pre>
  
  <p>but the question is: What if the email is passed trough the php file and no criteria is met?
  is there a way to
      <code>break</code> or
      <code>exit</code>
   and let postfix resume?</p>
  
  <p>For example the address: <code>info@domain.net</code> is an alias postfix should handle it.<br>
  but any digit email like <code>12345@domain.net</code> should be handled by the php filter.<br>
  but what if someone emails to a non existing email like <code>spam@domain.net</code></p>
  
  <p>As is: when using smtp (before queuing) the php filter is executed but when it's not a digit postfix isn't executed or at least not compared to the alias db.<br>
  when using the pickup (after queuing) postfix throws a 550 error (    Recipient address rejected: User unknown in virtual mailbox table
  ) when a digit email is send, because it doesn't exists in the alias db.</p>