ZyXEL Communications 91-009-073003B ユーザーズマニュアル

ZyWALL USG 50 User’s Guide

The anti-spam feature can mark or discard spam (unsolicited commercial or junk 
e-mail). Use the white list to identify legitimate e-mail. Use the black list to 
identify spam e-mail. The ZyWALL can also check e-mail against a DNS black list 
(DNSBL) of IP addresses of servers that are suspected of being used by 
spammers.

• Use  the  General screens (

) to turn anti-spam on or off 

and manage anti-spam policies.

• Use  the  Black/White List screens (

) to set up a black 

list to identify spam and a white list to identify legitimate e-mail. 

• Use  the  DNSBL screens (

) to have the ZyWALL check 

e-mail against DNS Black Lists.

Configure white list entries to identify legitimate e-mail. The white list entries have 
the ZyWALL classify any e-mail that is from a specified sender or uses a specified 
header field and header value as being legitimate (see 

 for more on mail headers). The anti-spam feature checks an e-mail against 

the white list entries before doing any other anti-spam checking. If the e-mail 
matches a white list entry, the ZyWALL classifies the e-mail as legitimate and does 
not perform any more anti-spam checking on that individual e-mail. A properly 
configured white list helps keep important e-mail from being incorrectly classified 
as spam. The white list can also increases the ZyWALL’s anti-spam speed and 
efficiency by not having the ZyWALL perform the full anti-spam checking process 
on legitimate e-mail.