Cisco Cisco Email Security Appliance C160 Mode D'Emploi
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Cisco AsyncOS 9.0 for Email User Guide
Chapter 9 Using Message Filters to Enforce Email Policies
Message Filter Actions
The Cisco message filters make a determination on whether a given MIME part is considered a message
“body” or a message “attachment”. The
“body” or a message “attachment”. The
html-convert()
filter only works on the message body parts.
For more information about message bodies and attachments, see
.
Depending on the format, the
html-convert()
filter uses different methods to strip the HTML from
within the documents.
If the message is plain text (text/plain), the message passes through the filter unchanged. If the message
is a simple HTML message (text/html), all the HTML tags are stripped out of the message and the
resulting body replaces the HTML message. The lines are not reformatted, and the HTML is not rendered
in plain text. If the structure is MIME (with a multipart/alternative structure) and it contains both a
text/plain part and text/html part with the same content, the filter removes the text/html part of the
message and leaves the text/plain part of the message. For all other MIME types (such as
multipart/mixed), all HTML body parts are stripped of their tags and reinserted into the message.
is a simple HTML message (text/html), all the HTML tags are stripped out of the message and the
resulting body replaces the HTML message. The lines are not reformatted, and the HTML is not rendered
in plain text. If the structure is MIME (with a multipart/alternative structure) and it contains both a
text/plain part and text/html part with the same content, the filter removes the text/html part of the
message and leaves the text/plain part of the message. For all other MIME types (such as
multipart/mixed), all HTML body parts are stripped of their tags and reinserted into the message.
When encountered in a message filter, the
html-convert()
filter action only tags the message to be
processed but does not immediately make a change to the message structure. The changes to the message
only take effect after all processing is complete. This allows the other filter actions to process the original
message body prior to modification.
only take effect after all processing is complete. This allows the other filter actions to process the original
message body prior to modification.
Bounce Profile Action
The
bounce-profile
action assigns a previously-configured bounce profile to the message. (See
.) If the message is undeliverable, the bounce options configured
via the bounce profile are used. Using this feature overrides the bounce profile assigned to the message
from the listener’s configuration (if one is assigned).
from the listener’s configuration (if one is assigned).
The following filter example assigns the bounce profile “fastbounce” to all email sent with the header
X-Bounce-Profile: fastbounce
:
Bypass Anti-Spam System Action
The
skip-spamcheck
action instructs the system to allow the message to bypass any content-based
anti-spam filtering configured on the system. This action does nothing to the message if no content-based
anti-spam filtering is configured, or if the message was never flagged to be scanned for spam in the first
place.
anti-spam filtering is configured, or if the message was never flagged to be scanned for spam in the first
place.
The following example allows messages that have a high SenderBase Reputation Score to bypass the
content-based anti-spam filtering feature:
content-based anti-spam filtering feature:
fastbounce:
if (header ('X-Bounce-Profile') == 'fastbounce') {
bounce-profile ('fastbounce');
}
whitelist_on_reputation:
if (reputation > 7.5)
{