This is a "good" error and means that the SEP-Server is up and running. You can easily verify this by sending secured email using global communication feature and you can read and reply securely.
If you browse to your SEP-server using https://sepserver.yourcompanyname.com you will receive an error saying:
The resource you are trying to access could not be found."
The reason for this is to avoid crawlers from search engines and others so all SEP servers in the world will be ignored by their search engines and similar services.