Error while sending email from Zoho email account

Error while sending email from Zoho email account

Hello Zoho Suport,

Hope you guys are doing well.

I'm getting following error when I try to send the email:
Unable to send message;Reason:554 5.1.8 Email Outgoing Blocked.

The email in concern is:
companyhub@zoho.com

Please assist.

Regards,
Amol
companyhub@zoho.com