McAfee SG310 Administration Manual page 230

Firewall menu options
Antivirus
From the Firewall menu, click Antivirus > SMTP email tab. The SMTP Email page appears
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(Figure 231).
Figure 231 SMTP Email
[Optional] Select the Virus check SMTP based email checkbox.
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[Optional] To send keep alive traffic to the source SMTP server, select the Send keep alive bytes to
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requesting server checkbox. This option is only useful on slow network connections where the source
server is timing out before the appliance has finished its virus checking.
[Recommended, enabled by default] To reject incoming mail with a virus detected, select the Inform
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requesting server of rejected mail checkbox. The appliance informs the requesting SMTP server when
mail has been dropped.
When the checkbox is cleared, the appliance accepts and then subsequently drops incoming mail
detected to contain a virus. The requesting mail server is unaware the mail was not delivered. The
appliance drops the mail without notification to the sender or requesting server.
Enter your SMTP mail server address of your LAN in the Destination SMTP server field.
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[Enabled by default] To enable source address translation, select the Source NAT connections
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checkbox. This enabled option prevents your mail server from being turned into an open relay if it is
configured to trust and forward messages appearing to originate from the LAN address of the appliance.
If enabled, the apparent source address for connections to the internal SMTP server is one of the WAN
addresses for the appliance. If disabled, the apparent source address is from the LAN side of the
appliance. An open relay configuration allows anyone on the Internet to send email through your
appliance.
[Optional] Enter a descriptive name in the SMTP Banner field. The name entered here appears in the initial
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text banner that is presented to incoming SMTP clients. The default is "SMTP Passthrough Proxy."
If you are experiencing time-out problems, adjust the value in the Network timeout field. Typically, the
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default is adequate.
• Default: 180 (seconds)
• Can be a value of 1 or greater
To set the maximum number of simultaneous SMTP connections, enter a value in the Maximum
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simultaneous SMTP sessions field. Increasing this value increases the resources consumed by virus
scanning.
• Default: 10
230 McAfee UTM Firewall 4.0.4 Administration Guide