A 530 error is very specific, it simply means that the username, password or account group provided do not match the server. This can be caused by two things:
1) THE ACCOUNT INFORMATION IN THE CLIENT DOES NOT MATCH THE ACCOUNT INFORMATION IN THE SERVER
On the RBS Server, endpoint is defined as belonging to an account. This value is used in the login, and all three values must match.
If you are sure that they match, there is a way to check. Look at the IP.LOG for that endpoint (the filename is the IP address.LOG). At the bottom you will find the most recent failed login attempt and that 530 error code is also right there. That almost always identifies whatever is wrong.
Set the Group for a new endpoint installation using the Server's Web Console. When that endpoint installation is distributed, the endpoint specified in the server will be the one used with whatever username and password are given to that endpoint.
You can chnage the Endpoint Group directly on a installed endpoint by editing the endpoint in the Web Console.
2) THE ENDPOINT IS ATTEMPTING TO CONTACT ANOTHER SERVER - NOT THE RBS SERVER
There are two possibilities:
A) If the RBS endpoint software is configured with the wrong IP address or port number, and there is a Server at the misconfigured IP address and port number, an error 530 may happen.
Reconfigure the endpoint software to call the correct Server.
B) If there is another Server application (like an FTP server or a Web server) running on the same computer as the RBS Server, it is possible that the other Server (instead of the RBS Server) is answering the incomming connection from the RBS endpoint. This can cause an Error 530 at the Client.
Turn OFF the other Server, or move it (or the RBS Server) to a non-conflicting port number.
FYI: If you have set your Command Port to 21, the Other Server is usually the Windows FTP Publishing Service or other FTP Server operating on Port 21.