ERROR_CODE :550, ERROR_CODE :Please turn on SMTP Authentication in your mail client.

ERROR_CODE :550, ERROR_CODE :Please turn on SMTP Authentication in your mail client.

Hello,
I am getting a bounce back with this error below. I verified MX records for fitsupply.com are correct and SPF records are correct. NOT SURE WHAT TO DO! Please help:

This message was created automatically by mail delivery software.

 A message that you sent could not be delivered to one or more of its recipients. This is a permanent error.

 

dlagers@scifit.com Invalid Address, ERROR_CODE :550, ERROR_CODE :Please turn on SMTP Authentication in your mail client.

                  sender1.zohomail.com [74.201.84.155]:29590 is not permitted to relay

                  through this server without authentication.

 

 

 Received:from NEWFITSERVER (71-8-117-68.dhcp.ftwo.tx.charter.com [71.8.117.68]) by mx.zohomail.com

      with SMTPS id 1419882919652296.05191121067537; Mon, 29 Dec 2014 11:55:19 -0800 (PST)  Message-ID:<05ad01d023a1$5e42d750$1ac885f0$@com>

 Date:Mon, 29 Dec 2014 13:55:15 -0600

 From:"Steve Blackburn" <sblackburn@fitsupply.com>  To:<dlagers@scifit.com>

 Subject:FW: PO#P7348A

 Content-Type:multipart/mixed;

      boundary="----=_NextPart_000_05AE_01D0236F.13A86750"