Before You Begin; The Anti-Spam General Screen; Figure 387 Dnsbl Example - ZyXEL Communications ZyWALL USG 300 User Manual

Figure 387 DNSBL Example

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1 The ZyWALL checks the e-mail's header for sender or relay IP addresses and sends
them to all of the DNSBL domains configured in the ZyWALL.
2 The DNSBL servers reply as to whether or not the IP addresses match an entry in their
list. In this example, DNSBL 1's reply came first. Since DNSBL 1 says the IP addresses
are not in its list, the ZyWALL waits for more responses.
3 DNSBL 2 has one of the IP addresses in its list.
4 The ZyWALL immediately classifies the e-mail as spam and takes the action for spam
that you defined in the anti-spam policy (in this example it was an SMTP mail and the
defined action is to drop the mail). After a positive match is found in a DNSBL, the
ZyWALL does not wait for any more DNSBL responses.

34.2 Before You Begin

Configure your zones before you configure anti-spam.

34.3 The Anti-Spam General Screen

Click Anti-X > Anti-Spam to open the Anti-Spam General screen. Use this screen to turn
the anti-spam feature on or off and manage anti-spam policies. You can also select the action
the ZyWALL takes when the mail sessions threshold is reached.
ZyWALL USG 300 User's Guide
1
IPs: a.b.c.d
w.x.y.z
Chapter 34 Anti-Spam
DNSBL 1
2
Not spam.
DNSBL 2
3
Spam!
DNSBL 3
543