Emails from a domain are not received and not in spam folder

Emails from a domain are not received and not in spam folder

We have trouble receiving emails sent from our server shameless-smoothies(dot)com. They do not arrive in any of our email addresses hosted at Zoho, nor can they be found in the spam folder. We can send emails to these addresses, but 9 out of 10 do not arrive.

We have tested extensively with other accounts hosted elsewhere - there were no problems receiving or sending emails from this server. I also tried whitelisting the domain and individual emails, but it did not solve the problem.

Would be fantastic if you can help as our product team must be able to communicate with the rest of the company.

Best regards,
Nadine