Cisco Cisco Email Security Appliance C170 사용자 가이드
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Cisco IronPort AsyncOS 7.6 for Email Configuration Guide
OL-25136-01
Chapter 5 Configuring the Gateway to Receive Email
Figure 5-2
Using the Cisco IronPort Appliance as an Enterprise Gateway
In this configuration, at least two listeners are required:
•
One listener configured specifically to accept mail from the Internet
•
One listener configured specifically to accept mail from your internal groupware and email servers
(POP/IMAP)
(POP/IMAP)
Public and Private Listeners
Consider the first listener a “public” listener and the second listener a “private” listener. Cisco IronPort
AsyncOS differentiates between public listeners — which by default have the characteristics for
receiving email from the Internet — and private listeners that are intended to accept email only from
internal (groupware, POP/IMAP, and other message generation) systems. Public and private listeners, by
default, have different features available to them and different default settings. By creating distinct
public and private listeners for different public and private networks, you can distinguish among email
for security, policy enforcement, reporting, and management. For example, email received on public
listeners is scanned by your configured anti-spam engine and the anti-virus scanning engine by default,
while email received on private listeners is not scanned. The same illustration, with listeners, is shown
in Figure 3-3.
AsyncOS differentiates between public listeners — which by default have the characteristics for
receiving email from the Internet — and private listeners that are intended to accept email only from
internal (groupware, POP/IMAP, and other message generation) systems. Public and private listeners, by
default, have different features available to them and different default settings. By creating distinct
public and private listeners for different public and private networks, you can distinguish among email
for security, policy enforcement, reporting, and management. For example, email received on public
listeners is scanned by your configured anti-spam engine and the anti-virus scanning engine by default,
while email received on private listeners is not scanned. The same illustration, with listeners, is shown
in Figure 3-3.
Internet
Groupware server
(Exchange™, Domino™,
Large Small
ISPs
IronPort Email Security appliance
SMTP
SMTP
Groupware client
Groupwise™)
corporations
corporations
POP/IMAP server
POP/IMAP client
Firewall