Sending email - Invalid Address, ERROR_CODE :550, ERROR_CODE :5.0.0 LOCAL-spammer range

Sending email - Invalid Address, ERROR_CODE :550, ERROR_CODE :5.0.0 LOCAL-spammer range

Switched to Zoho email yesterday.  I have been attempting to send an email to a contact at my server hosting provider and receive the  Invalid Address, ERROR_CODE :550, ERROR_CODE :5.0.0 LOCAL-spammer range error.  

How is this possible?  The domain is for a very reputable hosting company, and the specific email is to a support person that I've communicated with for several years until I switched to Zoho...

I've attempted to add both the domain and specific email to the anti-spam allowed domain and allow email lists to no avail.