Watchguard Firebox X20E, Руководство пользователя

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User Guide 117
Configuring the POP3 Proxy
Set the timeout to
This setting limits the number of seconds that the email client tries to open a connection to the
email server before the connection is closed. This prevents the proxy from using too many
network resources when the email server is slow or cannot be reached.
Set the maximum email line length to
This setting prevents some types of buffer overflow attacks. It is unlikely that you will need to
change this setting unless it prevents access to legitimate mail.
Deny Message
In the Deny Message field, you can write a custom plain text message that will appear in the
recipient email when the proxy blocks that email. You can use these variables:
%(type)%
Puts the content type of the email.
%(filename)%
Puts the name of the attached file.
%(virus)%
Puts the type of virus found.
%(action)%
Puts the action taken by the proxy policy.
%(reason)%
Puts the reason the proxy policy denied the content.
%(recovery)%
Puts whether you can recover the attachment.
It is important to know how the POP3 proxy denies email. When the proxy blocks a message because of
a header, you get a deny message instead of the email. When the proxy blocks an email message
because of body or attachment content and the email is less than 100 kilobytes, you get a deny mes-
sage instead of the email. If the proxy blocks an email message because of body or attachment content
and the email is larger than 100 kilobytes, you get a truncated version of the email or attachment and
the deny message is attached. When the POP3 proxy detects a protocol anomaly, or the email line
length exceeds the maximum email line length, the proxy blocks the message download and the user
gets no notification.You can see deny messages for this in the log messages. For information on using
the log message tool, see Chapter 11, “Logging and Certificates.”