unable to receive email using Zoho

unable to receive email using Zoho

I am able to send email and have the user client will receive it, but when they attempt to respond they continually get the following error.


This message was created automatically by mail delivery system. 

THIS IS A WARNING MESSAGE ONLY. 

YOU DO NOT NEED TO RESEND YOUR MESSAGE. 

The original message was received at Thu, 07 Dec 2017 18:20:49 -0800 
from  ddefuria@scatutoring.com  [ ddefuria@scatutoring.com ] 

----- The following addresses had fatal errors ----- 
[Status: DOMAIN_NOT_RESOLVED, Address: < ddefuria@scatutoring.com >, DOMAIN_NOT_RESOLVED] 

Message will be retried for 4 more day(s) 

----- Transcript of session follows ----- 

Received:from mail.zoho.com by mx.zohomail.com 
    with SMTP id 151269694293147.79992685927732; Thu, 7 Dec 2017 17:35:42 -0800 (PST) 
Message-ID:<16033c39152.116be 1e0c130652.8043468042022070133@scatutoring.com > 
Date:Thu, 07 Dec 2017 17:35:42 -0800 
From:Danielle DeFuria < ddefuria@scatutoring.com > 
User-Agent:Zoho Mail 
To:"Danielle DeFuria" < ddefuria@scatutoring.com > 
Subject:test 
Content-Type:multipart/alternative; 
    boundary="----=_Part_416711_1440691624.1512696942930"