Unable to send message;Reason:550 5.4.6 Mail rate exceeded limit

Unable to send message;Reason:550 5.4.6 Mail rate exceeded limit

Dear Support,

By mistake Our Employee send numbers of email through info@hotelkeycardprint.com
Now i am getting below message.
Unable to send message;Reason:550 5.4.6 Mail rate exceeded limit. Click here to unblock.

Please Unblock my account but we will take care in future...

Regards
Akansh