Undelivered Mail Returned to Sender: ERROR_CODE :550, ERROR_CODE :5.7.1

Undelivered Mail Returned to Sender: ERROR_CODE :550, ERROR_CODE :5.7.1

Hi all,

I am having problem when send the email to gmail with below details: 
""
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. 

xyz@gmail.com, ERROR_CODE :550, ERROR_CODE :5.7.1 This message does not have authentication information or fails to pass 
            5.7.1 authentication checks. To best protect our users from spam, the 
            5.7.1 message has been blocked. Please visit 
            5.7.1 https://support.google.com/mail/answer/81126#authentication for more 
            5.7.1 information. f18si5408752ejk.162 - gsmtp 



Received:from [192.168.100.6] (123.16.66.253 [123.16.66.253]) by mx.zohomail.com 
    with SMTPS id 1550046099652649.1521288605221; Wed, 13 Feb 2019 00:21:39 -0800 (PST) 
Message-ID:<B8B969E7-1F6D-4AF3-BBA1-F5E98096D12A@etsa.vn> 
Date:Wed, 13 Feb 2019 15:21:29 +0700 
From:<abc@etsa.vn> 
User-Agent:Microsoft-MacOutlook/10.10.2.180910 
To:<xyz@nldc.evn.vn> 
Cc:<zyx@gmail.com> 
Subject:Re: Sơ đồ phương thức Phước Hữu - 
Điện Lực 1 
Content-Type:multipart/mixed; 
    boundary="B_3632916090_2088264310" 
"""
Please help me to trouble this problem. Our domain is etsa.vn.

Thanks and best regards.