An administrator manipulated the subnet mask but was still unable to access the user interface.

If you are unable to access the user interface of the Cisco Secure Email Gateway appliance after manipulating the subnet mask, you can use the serial or console port to perform the initial configuration.  The serial or console port provides a command-line interface that allows you to configure basic network settings such as IP address, subnet mask, gateway, and hostname 3 . References =  User Guide for AsyncOS 12.0 for Cisco Email Security Appli ances - GD (General Deployment) - Configuring Network Settings [Cisco Secure Email Gateway] - Cisco