NAME
spamoracle.conf - SpamOracle configuration file format
DESCRIPTION
The spamoracle.conf file is a configuration file governing the
operation of the spamoracle(1) e-mail classification tool. By default,
the configuration file is searched in $HOME/.spamoracle.conf but an
alternate location can be specified using the -config flag to
spamoracle(1).
Important note: most of the configuration parameters should not be
modified lightly, as this may result in completely wrong e-mail
classification. Familiarity with Graham’s filtering algorithm, as
described in the paper referenced at the end of this page, is required
to really understand the effect of the parameters.
SYNTAX
The spamoracle.conf file is composed of lines of the form variable =
value. Lines starting with a hash sign (#) are treated as comments and
ignored. Blank lines are ignored.
Depending on the type of the variable (see the list of variables
below), the value part is of the following forms:
string A sequence of characters. Blanks (spaces, tabs) at the
beginning and the end of the string are ignored. Alternatively,
the string can be enclosed in double quotes ("), in which case
spaces are not trimmed. Inside quoted strings, blackslashes (
and double quotes (") must be escaped with a backslash, as in \
or
boolean
Either on, yes, true, or 1 to activate the boolean option, or
off, no, false, or 0 to deactivate it.
integer
A decimal integer
float A decimal floating-point number.
regexp A regular expression in emacs(1) syntax. The repetition
operators are *, +, and ?. Alternation is written \| and
grouping is written \(...\). Character classes are written
between brackets [...] as usual. A single dot denotes any
character except newline. Regular expressions are case-
insensitive.
CONFIGURABLE PARAMETERS
database_file
(type string, default value $HOME/.spamoracle.db )
The location of the file that contains the database of word
frequencies used by spamoracle(1).
html_retain_tags
(type boolean, default value false)
In HTML-formatted e-mails and attachments, the names of HTML
tags are normally not treated as words and are ignored for the
word frequency calculations. If the html_retain_tags parameter
is set to true, HTML tags (such as img or bold) are treated as
words and included in the computation of word frequencies.
html_tag_attributes
(type regexp, default value
a/href\|img/src\|img/alt\|frame/src\|font/face\|font/color)
This regular expression matches pairs of HTML tags and HTML
attributes written as tag/attribute. When scanning HTML-
formatted e-mails and attachments, attributes to HTML tags are
normally ignored, unless the tag/attribute pair matches the
regular expression html_tag_attributes. If the tag/attribute
pair matches this regexp, the value of the attribute (for
instance, the URL for the a/href attribute) is scanned for
words.
mail_headers
(type regexp, default value from:\|subject:)
A regular expression determining which headers of an e-mail
message are scanned for words.
spam_header
(type string, default value X-Spam)
The name of the header that spamoracle mark adds to incoming e-
mail messages, with the results of the spam/non-spam
classification.
attachments_header
(type string, default value X-Attachments)
The name of the header that spamoracle mark adds to incoming e-
mail messages, with the one-line summary of attachment types,
names and character sets. The generation of this header can be
turned off with the summarize_attachment parameter.
summarize_attachment
(type boolean, default value true)
If this parameter is set, spamoracle mark generates a one-line
summary of the attachments of the incoming messages, and inserts
this summary in the message headers. Setting this parameter to
false disables the generation of this extra header.
num_meaningful_words
(type integer, default value 15)
Maximal number of "meaningful" words that are retained for
computing the spam probability. During mail analysis,
spamoracle extracts all words of the message, and retains those
whose spam frequency (frequency of occurrence in spam messages)
is closest to 1 or to 0. At most num_meaningful_words such
"meaningful" words are retained.
max_repetitions
(type integer, default value 2)
Maximum number of times a given word can occur in the set of
"meaningful" words retained for computing the spam probability.
The default value of 2 means that at most 2 occurrences of the
same word will be retained.
low_freq_limit
(type float, default value 0.01)
high_freq_limit
(type float, default value 0.99)
The spam frequency of a word is computed as the number of
occurrences in spam divided by number of occurrences in all
messages. This ratio is then clipped to the interval [
low_freq_limit, high_freq_limit ], so that words that are
extremely rare or extremely common in spam do not bias the
probability computation too much. The default values of 0.01
and 0.99 are adequate for a corpus of a few thousand e-mails.
For larger corpora (e.g. 10000 e-mails), the values 0.001 and
0.999 may give better results.
min_meaningful_words
(type integer, default value 5)
Minimum number of "meaningful" words below which spamoracle mark
refuses to classify the e-mail and outputs "unknown" status.
This happens with very short e-mails, or e-mails that consist
exclusively of links and pictures.
good_mail_prob
(type float, default value 0.2)
Spam probability below which the e-mail is classified as non-
spam.
spam_mail_prob
(type float, default value 0.8)
Spam probability above which the e-mail is classified as spam.
Messages whose probability falls between good_mail_prob and
spam_mail_prob are classified as "unknown".
AUTHOR
Xavier Leroy <Xavier.Leroy@inria.fr>
SEE ALSO
spamoracle(1)
http://www.paulgraham.com/spam.html (Paul Graham’s seminal paper)