Android Secure Mail Error "THE VPN SERVICE HAS FAILED TO CONNECT"

Secure Mail users receive an error : The VPN service has failed to connect. In the Secure mail logs we find : "2017-03-21T15:30:42.260+0800","MDX-ErrorCodes","WARNING 3","ErrorCodes = 507 507 = Vpn "2017-03-21T15:30:43.946+0800","MDX-ErrorCodes","WARNING 3","ErrorCodes = 602 602 = VpnFailedOption...