Gateway or firewall or mailhub channel options

There are a number of channel options of particular interest when configuring channels intended to communicate with gateway, firewall, or mailhub systems.

See also:
 * aliasdetourhost Option
 * aliasoptindetourhost Option
 * clonehosts Option
 * daemon Option
 * lastresort Option
 * multigate Option
 * nomultigate Option
 * user Option
 * Functional group list of channel options