3Com 3CR3MFA-92, Руководство пользователя

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50 C
HAPTER
4: A
NTI
-S
PAM
C
ONFIGURATION
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Redirect to: The message will be delivered to the mail address
specified in Action Data.
■
Reject mail: The mail will not be accepted and the connecting mail
server is forced to return it.
■
BCC (Blind Carbon Copy): The message will be copied to the mail
address specified in Action Data.
■
Action data — Depending on the specified action:
■
Modify Subject Header: The specified text will be inserted into the
subject line, such as [BULK].
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Add header: A message header will be added with the specified
text, such as [BULK].
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Redirect to: Send the message to a mailbox such as
spam@example.com
.
STA
STA (Statistical Token Analysis) is a sophisticated method of identifying
spam based on statistical analysis of mail content. Simple text matches
can lead to false positives because a word or phrase can have many
meanings depending on the context. STA provides a way to accurately
measure how likely any particular message is to be spam without having
to specify every word and phrase.
STA achieves this by deriving a measure of a word or phrase contributing
to the likelihood of a message being spam. This is based on the relative
frequency of words and phrases in a large number of spam messages.
From this analysis, it creates a table of “discriminators” (words associated
with spam) and associated measures of how likely a message is spam.
When a new incoming message is received, STA analyzes the message,
extracts the discriminators (words and phrases), finds their measures from
the table, and aggregates these measures to produce a spam metric for
the message between 1 and 100.
STA uses three sources of data to build its run-time database:
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The initial database tables based on analysis of known spam.
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Tables derived from an analysis of local legitimate mail. This is referred
to as “training.”