5.1.8 Email Outgoing Blocked

5.1.8 Email Outgoing Blocked

Hi.

I'm unable to send any e-mails with the following error message continuously popping up:

"An error occurred while sending mail. The mail server responded:  5.1.8 Email Outgoing Blocked. <a href= https://www.zoho.com/mail/help/usage-policy.html target=_blank>Learn more.</a>. Please check the message and try again.".

Could someone please fix it for me?

Thanks