Hi,

Your message to the following recipient was not delivered. Please find the details below. 

Bounce Details:
Bounced Address :  someone@google.com
Bounce Reason : other ; Status : 5.0.0 (undefined status) ; Daignostic-Code : smtp;542  s omeone@google.com  Rejected ;
Bounced Time : Sep 05, 2017 06:37 PM BST


Regards,
Zoho Team

The email addresses were fine only a few days ago but are now being rejected ?