Unusual activity detected. Your account is locked from sending emails.

Unusual activity detected. Your account is locked from sending emails.

Honestly, I do not know what is going on. I only have one email unable to send in outbox. I've enabled 2FA. How do I resolve this? This is the message I got when I visit https://mail.zoho.com/UnblockMe

Account block information

Your account has been blocked due to security reasons. Click here to read about our usage policy.

Blocks list
  1. Mail Outgoing block: Account has been blocked due to security reasons.