SMTP error

Hello,
I would like to fix a problem which is i am not able to send emails form my wordpress hosted on aws.
on the other hand i have zoho mail configured on my DNS (godaddy) and working.
i am using "WP Mail SMTP Settings" as a plugin when i try to test an email i got the following:

[ErrorInfo] => SMTP Error: data not accepted.SMTP server error: DATA END command failed Detail: Transaction failed: Invalid domain name: 'xx.xxx.38.73'.
SMTP code: 554
[From] => wordpress@xx.xxx.38.73

Kindly can someone tell me what to troubleshoot?
Regards,