CAN NOT SENT EMAIL FROM ZOHO MAIL

CAN NOT SENT EMAIL FROM ZOHO MAIL

I've tried to address this in the forums below but my replies never get posted.

I do not know if my email accounts require authorization to send, the hosts do not indicate this in any way. I set the preferences as if they did require authorization just to experiement, but it made not difference, I still can not send.

To describe the problem again, this is the error message I receive if I try to send out from any of my three email accounts set up in Zoho Mail:

Sending failed; Reason:550 5.7.1 <brea.plum@chilterncom>... Relaying denied. IP name lookup failed [72.5.230.65]