Mail Delivery Issues

Hi,

We have experience problem with our zoho mail when we switch to Hostpapa yesterday.

The error that the other server returned was:
550-Please turn on SMTP Authentication in your mail client.
550-mail-vk0-f54.google.com [209.85.213.54 ]:34285 is not permitted to relay
550 through this server without authentication.

I have added the records in the DNS Manager

How can I rectify the issues?

Thanks.