Hi,

I'm writing since we started to receive bounced emails from one of our recipients. I am able to send email to that recipient from my gmail, but when I send from zoho, I receive following error. 

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.

xxx@xx.com INVALID_ADDRESS, ERROR_CODE :550, ERROR_CODE :5.1.1 Error: invalid recipients is found from 135.84.80.217

Nerses