Table of Contents
Defining actions and headers
After checking message contents, the filter assigns a global score to the message. ze-filter can take different actions depending on the global score assigned to the message or to scores assigned by each kind of check.
Possible actions (with their official names) are :
Actions and their conditions are defined, at ze-filter configuration file, by rules :
XSTATUS_xxx_CONDITION condition; condition; ...
where xxx is one possible action, as defined above. Actions are checked in the same order defined above. After a condition matches, the filter stops looking for other possible actions.
Each condition is of the form :
parameter operator value
parameter is one of :
- score - global score
- bayes - naive bayes filter score
- urlbl - URL filtering score
- regex - pattern matching score
- urlbl+regex or regex+urlbl - trivial, it seems…
- oracle - heuristic filter score
- header - just added X-ze-filter-Score header
An example of condition is :
XSTATUS_REJECT_CONDITION score > 0.75; urlbl > 19; header ~ R=##.*U=####
This means : the message will be rejected :
- if global score is greater than 0.75
- if the URLBL score is greater than 19
- if the just added X-ze-filter-Score header matches R=##.*U=#### regular expression
To define which header will be added or changed :
X-ze-filter-Status. Some other filters use something different, e.g.
X-Spam-Flag. MUAs like thunderbird can integrate some of these headers in their filtering. This is, probably, the easiest way to integrate ze-filter results into the MUA filtering.
# Adds - X-ze-filter-Status: Spam HI XSTATUS_HEADER_HI_CONDITION score > 0.75 # Adds - X-ze-filter-Status: Spam LO XSTATUS_HEADER_LO_CONDITION score > 0.5 # Adds - X-ze-filter-Status: Unsure XSTATUS_HEADER_UNSURE_CONDITION score > 0.25 # Adds - X-ze-filter-Status: Ham XSTATUS_HEADER_HAM_CONDITION score < 0.25
Changing Message Subject
You should avoid changing message subject but, unfortunately, you may want/need this feature.
To enable/disable this feature, use the SCORE_ON_SUBJECT configuration option.
SCORE_ON_SUBJECT YES SCORE_ON_SUBJECT_TAG ***SPAM***
Rejecting the message during SMTP session
XSTATUS_REJECT_CONDITION bayes > 3.8; urlbl > 89
Discarding and quarantining
XSTATUS_QUARANTINE_CONDITION bayes > 0.8; urlbl > 19; (U=######|B=0.9|B=0.8|XXXX.*B=0.7)
More info about quarantine management
Preserving or removing old score headers
Sometimes you may want to remove previously added ze-filter headers and let only those added by your mail server or some known mail servers. You can do this with the PRESERVE_OLD_SCORES.
There are three possible situations :
- Preserve all headers - This is the default value, and is enabled if the value of this option is ALL or an empty string.
- Remove all previous ze-filter headers - To enable this behaviour, set PRESERVE_OLD_HEADERS to NONE
- Preserve only headers added by some list of mailservers - Define the list of mailservers, separated by a space or a comma :
PRESERVE_OLD_SCORES smtp.example.com, mail.domain.com