CAN NOT SEND EMAILS FROM ZOHO VO

CAN NOT SEND EMAILS FROM ZOHO VO

I posted about this problem earlier with no response, let's try again:

If I try to reply to an email or send and email, I get this error message:

Sending failed; Reason:550 5.7.1 <recipient's email address>... Relaying denied. IP name lookup failed [64.41.199.18]

All the outgoing server information entered into VO preferences is correct. Please advise.