Unable to send message;Reason:554 5.1.8 null

I found a reply which was below and someone from zoho replied that all thing are good now i can use zoho mail but it showing same error so please take serious and do needful.

Hi,

Arivalagan A has replied to the topic you follow.,
Unable to send message;Reason:554 5.1.8 Sender Address Blocked.

Hello,

Thank you for writing to us.

We've unblocked the account as requested and everything will be working fine now.

Please shout out to us if we can be of any further assistance.

Regards,
Arivalagan.A | Zoho Mail Support