I set my COS "password area" to lock the account after three times failure, is it possible to add alert to the admin when the account locked, and how do I change the default text from the webmail client because when the client trying to login but the message is not cleared appearing.

There is no different between the wrong password and when the account locked "The username or password is incorrect. Verify that CAPS LOCK is not on, and then retype the current username and password. "