ZyXEL Communications 5 Series - Manual (Page 289)

ZyWALL 5/35/70 Series User’s Guide
Chapter 15 Anti-Spam 289
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, choose what traffic flows the ZyWALL checks for spam,
and set how the ZyWALL treats spam.