Error: Unable to send message: Reason 550 5.4.6 mail rate exceeded limit

Error: Unable to send message: Reason 550 5.4.6 mail rate exceeded limit

Do You have a permanent solution to this? It's very annoying when it happens regularly, and we have to unblock it every now and again.
Is there some setting to permanent unblock this?

it is used for activation purpose and not bulk mail.