ZyXEL Communications 70 Series User Manual

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ZyWALL 5/35/70 Series User’s Guide
Chapter 15 Anti-Spam
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15.1.7  MIME Headers
MIME (Multipurpose Internet Mail Extensions) allows varied media types to be used in e-
mail. MIME headers describe an e-mail’s content encoding and type. For example, it may 
show which program generated the e-mail and what type of text is used in the e-mail body. 
Here are some examples of MIME headers: 
• X-Priority: 3 (Normal)
• X-MSMail-Priority: Normal
• Content-Type: text/plain; charset="iso-8859-1"
• Content-Transfer-Encoding: base64
In an MIME header, the part that comes before the colon (:) is the header. The part that comes 
after the colon is the value. Spam often has blank header values or comments in them that are 
part of an attempt to bypass spam filters.
15.2  Anti-Spam General Screen
Click SECURITY, ANTI-SPAM to open the Anti-Spam General screen. Use this screen to 
turn the anti-spam feature on or off and set how the ZyWALL treats spam.  
Figure 125   Anti-Spam: General