Cisco Cisco Email Security Appliance C170 Guia Do Utilizador
13-5
Cisco AsyncOS 8.0.1 for Email User Guide
Chapter 13 Anti-Spam
Cisco Intelligent Multi-Scan Filtering
Step 3
Click Edit Global Settings.
Step 4
Select the check box for Enable IronPort Anti-Spam Scanning.
Checking this box enables the feature globally for the appliance.
Step 5
To optimize the throughput of your appliance while still being able to scan increasingly larger messages
sent by spammers, configure the thresholds for message scanning by Cisco Anti-Spam.
sent by spammers, configure the thresholds for message scanning by Cisco Anti-Spam.
Step 6
Submit and commit your changes.
Cisco
Intelligent Multi-Scan Filtering
Cisco Intelligent Multi-Scan incorporates multiple anti-spam scanning engines, including Cisco
Anti-Spam, to provide a multi-layer anti-spam solution.
Anti-Spam, to provide a multi-layer anti-spam solution.
When processed by Cisco Intelligent Multi-Scan:
•
A message is first scanned by third-party anti-spam engines.
Option
Description
Message
Scanning
Thresholds
Scanning
Thresholds
a.
Enter a value for Always scan messages smaller than—The recommended
value is 512 Kb or less. Messages smaller than the always scan size will be fully
scanned, except in cases of “early exit.” Messages larger than this size are
partially scanned if they are smaller than the never scan size
value is 512 Kb or less. Messages smaller than the always scan size will be fully
scanned, except in cases of “early exit.” Messages larger than this size are
partially scanned if they are smaller than the never scan size
Cisco advises not to exceed 3 MB for the always scan message size. A larger
value may result in decreased performance.
value may result in decreased performance.
b.
Enter a value for Never scan messages larger than—The recommended value
is 1024 Kb or less. Messages larger than this size will not be scanned by Cisco
Anti-Spam and the
is 1024 Kb or less. Messages larger than this size will not be scanned by Cisco
Anti-Spam and the
X-IronPort-Anti-Spam-Filtered: true
header will not be
added to the message.
Cisco advises not to exceed 10 MB for the never scan message size. A larger
value may result in decreased performance.
value may result in decreased performance.
For messages larger than the always scan size or smaller than the never scan size, a
limited and faster scan is performed.
limited and faster scan is performed.
Note
If the Outbreak Filters maximum message size is greater than Cisco
Anti-Spam’s always scan message, messages smaller than the Outbreak
Filters maximum size are fully scanned.
Anti-Spam’s always scan message, messages smaller than the Outbreak
Filters maximum size are fully scanned.
Timeout for
Scanning
Single
Message
Scanning
Single
Message
Enter the number of seconds to wait for timeout when scanning a message.
Enter an integer from 1 to 120. The default value is 60 seconds.
Regional
Scanning
Scanning
Enable or disable regional scanning and if applicable, select a region.
Enable this feature only if you receive the bulk of your email from the specified
region. Because this feature optimizes the anti-spam engine for a particular region, it
can reduce capture rates for other types of spam.
region. Because this feature optimizes the anti-spam engine for a particular region, it
can reduce capture rates for other types of spam.