Unable to send message: Reason:550 5.4.6 Unusual sending activity detected

Unable to send message: Reason:550 5.4.6 Unusual sending activity detected

Today one of our accounts had a problem in one of our email sending systems, which ended up sending several repeated emails (we've already stopped sending through this system, until we fixed it).

I tried to unblock the account via the following link: https://mail.zoho.com/UnblockMe
But on the page it says that my account is not blocked, is there a way to fix it?