F-SECURE ANTI-VIRUS FOR MICROSOFT EXCHANGE 7.10 Administrator's Manual page 69

Network Configuration
The mail direction is based on the Internal Domains and Internal SMTP
hosts settings. For more information, see
Internal Domains
Internal SMTP
Senders
Centrally Managed Administration
"Network
Specify internal domains. Messages coming to
internal domains are considered to be inbound
mail unless they come from internal SMTP
sender hosts.
Separate each domain name with a space. You
can use an asterisk (*) as a wildcard. For
example, *example.com internal.example.net
Specify the IP addresses of hosts that belong to
your organization. Specify all hosts within the
organization that send messages to Exchange
Edge or Hub servers via SMTP as Internal
SMTP Senders.
Separate each IP address with a space. An IP
address range can be defined as:
a network/netmask pair (for example,
10.1.0.0/255.255.0.0), or
a network/nnn CIDR specification (for
example, 10.1.0.0/16).
You can use an asterisk (*) to match any number
or dash (-) to define a range of numbers. For
example,
172.16.4.4 172.16.*.1 172.16.4.0-16
172.16.250-255.*
CHAPTER 5
Configuration", 56.
69