Cisco Cisco Email Security Appliance C190 Guía Del Usuario
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Cisco AsyncOS 9.1 for Email User Guide
Chapter 9 Using Message Filters to Enforce Email Policies
Message Filter Rules
Random Rule
The
random
rule generates a random number from zero to N-1, where N is the integer value supplied in
parenthesis after the rule. Like the
header()
rule, this rule may be used in a comparison, or may be used
alone in a “unary” form. The rule evaluates to
true
in the unary form if the random number generated
is non-zero. For example, both of the following filters are effectively equal, choosing Virtual Gateway
address A half the time, and Virtual Gateway address B the other half of the time:
address A half the time, and Virtual Gateway address B the other half of the time:
Recipient Count Rule
The
rcpt-count
rule compares the number of recipients of a message against an integer value, in a
similar way to the
body-size
rule. This can be useful for preventing users from sending email to large
numbers of recipients at once, or for ensuring that such large mailing campaigns go out over a certain
Virtual Gateway address. The following example sends any email with more than 100 recipients over a
specific Virtual Gateway address:
Virtual Gateway address. The following example sends any email with more than 100 recipients over a
specific Virtual Gateway address:
load_balance_a:
if (random(10) < 5) {
alt-src-host('interface_a');
} else {
alt-src-host('interface_b');
}
load_balance_b:
if (random(2)) {
alt-src-host('interface_a');
} else {
alt-src-host('interface_b');
}
large_list_filter:
if (rcpt-count > 100) {
alt-src-host('mass_mailing_interface');
}