Plz be noted that we are associate our domain with you also Mx record but suddenly today we are not getting our mails niether send nor recvd so plz check at your end what is the problem, our domain is Sunshinelogsitics.com.pk

Further we got below MSG when we send any mail 

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 Sun, 03 Dec 2017 21:17:11 -0800
 from kashif@sunshinelogistics.com.pk [ kashif@sunshinelogistics.com.pk]

    ----- The following addresses had fatal errors -----   
   [Status: DOMAIN_NOT_RESOLVED, Address: < uzair@sunshinelogistics.com.pk>, DOMAIN_NOT_RESOLVED, Status: DOMAIN_NOT_RESOLVED, Address: < farhan@sunshinelogistics.com.pk>, 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 151236191749568.02463552770678; Sun, 3 Dec 2017

Thanks 

Kashif