title: Sending bulk emails through SMTP or EWS to avoid being marked as a spam?
body: <ul>
  <li><p>Does sending emails through SMTP actually helps in avoiding being marked as a spam domain?</p></li>
  <li><p>What about EWS (Exchange Web Services)? If I use EWS to send bulk emails, will my chances in being marked as a spam domain increase or decrease or is it irrelevant?</p></li>
  </ul>
  
  <p><em>Back Story:</em>
  I'm trying to figure out the best way to send bulk emails without getting my domain marked as a spam domain.
  So far I settled on using EWS, however my colleagues at work informed me that using EWS will be a bad idea as your domain will eventually get marked as a spam domain (by google.com, outlook.com, yahoo.com, etc..) but if SMTP were to be used, then you can avoid this problem.</p>
  
  <p>I searched SO but almost all the questions that have been asked here are in context of technique used to send emails. (check notspam.com or dnsrbl.org to diagnose and check email headers) 
  But I couldn't find a question that will answer which method is advantageous in term of avoiding being marked as spam. </p>