title: What does this error means using SwiftMailer via SMTP "554 Too many nonmail command"?
body: <p>I am currently using SwiftMailer SMTP to send a large number (around 4000 addresses) of emails using BCC with an application Im developing with PHP, but I keep getting this error</p>
  
  <blockquote>
    <p>Fatal error: Uncaught exception 'Swift_TransportException' with message 'Expected response code 250 but got code "554", with message "554 Too many nonmail commands "' in /home/childsur/public_html/plugins/swiftmail/lib/classes/Swift/Transport/AbstractSmtpTransport.php:386</p>
  </blockquote>
  
  <p>What does this error means and how can it be rectified?</p>
  
  <p>Thanks in advance</p>