Symantec Mail Security, Руководство администратора

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96 Configuring email filtering
Managing Email Firewall policies
Symantec Mail Security for SMTP lets you customize spam detection in the
following ways:
■
Define Allowed Senders
Symantec Mail Security for SMTP treats mail coming from an address or
connection in an Allowed Senders List as legitimate mail. As a result, you
ensure that such mail is delivered immediately to the inbox, bypassing any
other filtering. The Allowed Senders Lists reduce the small risk that
messages sent from trusted senders will be treated as spam or filtered in
any way.
■
Define Blocked Senders
Symantec Mail Security for SMTP supports a number of actions for mail
from a sender or connection in a Blocked Senders List. As with spam
verdicts, you can use policies to configure a variety of actions to perform on
such mail, including deletion, forwarding, and subject line modification.
■
Use the Sender Reputation Service
By default, Symantec Mail Security for SMTP is configured to use the
Sender Reputation Service. Symantec monitors hundreds of thousands of
email sources to determine how much email sent from these IP addresses is
legitimate and how much is spam. The service currently includes the
following lists of IP addresses, which are continuously compiled, updated,
and incorporated into Symantec Mail Security for SMTP filtering processes
at your site:
■
Open Proxy Senders
IP addresses that are either open proxies used by spammers or
“zombie” computers that have been co-opted by spammers.
■
Safe Senders
IP addresses from which virtually no outgoing email is spam.
■
Suspected Spammers
IP addresses from which virtually all of the outgoing email is spam.
No configuration is required for these lists. You can choose to disable any of
these lists.
■
Incorporate lists managed by other parties
Third parties compile and manage lists of desirable or undesirable IP
addresses. These lists are queried using DNS lookups. When you configure
Symantec Mail Security for SMTP to use a third-party sender list, Symantec
Mail Security for SMTP checks whether the sending mail server is on the
list. If so, Symantec Mail Security for SMTP performs a configured action,
based on the policies in place.