User Guide

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AsyncOS 9.1.2 for Cisco Email Security Appliances User Guide
Chapter 9 Using Message Filters to Enforce Email Policies
Message Filter Rules
Sender Group Rule
The sendergroup message filter selects a message based on which sender group was matched in a
listener's Host Access Table (HAT). This rule uses '==' (for matching) or '!=' (for not matching) to test
for matching a given regular expression (the right side of the expression). For example, the following
message filter rule evaluates to
true if the sender group of the message matches the regular expression
Internal, and, if so, sends the message to an alternate mail host.
Body Size Rule
Body size refers to the size of the message, including both headers and attachments. The body-size rule
selects those messages where the body size compares as directed to a given number. For example, the
following filter bounces any message where the body size is greater than 5 megabytes.
The
body-size can be compared in the following ways:
{
skip-filters();
}
senderGroupFilter:
if (sendergroup == "Internal")
{
alt-mailhost("[172.17.0.1]");
}
BigFilter:
if (body-size > 5M)
{
bounce();
}
Example Comparison Type
body-size < 10M
Less than
body-size <= 10M
Less than or equal
body-size > 10M
Greater than
body-size >= 10M
Greater than or equal
body-size == 10M
Equal
body-size != 10M
Not equal