How i fix: "unusual activity detected on this IP. Try again later"?

How i fix: "unusual activity detected on this IP. Try again later"?

Hello i have tried to create a new accont mail for my domain today, and In my bussines we have a 16 mail acconts and a get a message like: 
"Unusual activity detected on this IP. Try again later". I tried to create in a other computer and appears the same notification. How i fix this?