SpamWall Operations Manual

Tuning the SpamWall System

The SpamWall system in it's default configuration with it's multi-layer Spam Filtering Technology and default set of Spam Scoring Levels is able to detect and block or filter up to 98% of all Spam/UCE received by the system.

The Spam Scanning & Filtering Engine on the SpamWall system also incorporates a number of "self-tuning" and "auto-learning" mechanisms including Bayesian Analysis and Learning which are able to automatically increase accuracy and sensitivity of the system over time.

It is also possible to increase the percentage of Spam/UCE detected and either blocked, quarantined or tagged by modifying the "Spam Score Levels" in the Spamfilter Config screen of the SpamWall control panel.

Once you have been administering your SpamWall system for a while and have a good overview of which emails are processed, tagged and quarantined by the system you will be able to determine the optimum Spam Scoring Levels for your particular application.

By "tuning" the system over time you will be able to achieve the optimum level of Spam/UCE detection and management for your particular email user base and the specific type and content of email messages received by your users.

Spam Scoring Tag Levels

The default "Tag Level" refers to the minimum Spam Score of an email message before it is tagged or "flagged" as being possible Spam/UCE. Messages scoring over this level will cause the system to the add "X-Spam-Status" and "X-Spam-Level" headers to the email so that they can be identified on the recipient end if necessary as being Spam or not-Spam and at what Spam Score Level the message has been assessed at.

Tuning The SpamWall Scores

The default "Advanced Tag Level" will mark a message as Spam/UCE by appending the "[SPAM?]" type tag to the message "Subject" line when it scores 5 points or more. The "X-Spam-Status" tag is also changed from "No" to "Yes" at this level.

The default "Action/Kill Level" is set at "12". Messages scoring over this level will be sent to the Spam Quarantine.

A summary of these actions would be as follows:

Tag Level:           when to add "X-Spam-Status" and "X-Spam-Level" headers
Advanced Tag Level:  when to add "X-Spam-Flag: YES" and edit the subject line
Action/Kill Level:   when to take action sending message to the Spam Quarantine

Reducing these Spam Scoring default levels will detect more Spam/UCE, but it may also potentially increase the number of "false positives", this being legitimate email being blocked, quarantined or tagged as Spam.

In it's default configuration the SpamWall system is designed to minimize false positives. With no additional configuration or tuning the false positive rate is typically at less than 0.1%, or less than one in every 10,000 email messages processed by the system.

In addition to its low false positive rates, the SpamWall system can be configured with a Spam Scoring "Action/Kill Level" which is high enough that that even messages which are likely to be Spam/UCE are not blocked or quarantined but rather marked with the "[SPAM?]" tag and "X-Spam-Status" and "X-Spam-Level" headers and forwarded on to the intended recipient.

Once received these tagged messages can then either be checked visually to see if there are any legitimate messages or otherwise the user can set up their email client to detect and divert any tagged messages to a "Spam" or "Junk" folder or mailbox.

In general, the Spam Scoring "Action/Kill Level", which is set at "12" by default, should be kept reasonably high until you become familiar with administering your SpamWall system as if this value is set too low this may increase the possibility of a legitimate email message being sent to the Spam Quarantine, in which case you may have to retrieve it at the request of a user or otherwise check the Spam Quarantine more carefully or more regularly to ensure that there are no legitimate emails of any significance being sent there.

The default Spam Scoring values set on the SpamWall system are quite conservative so as to minimize the chance of any legitimate emails being blocked or directed to the Spam Quarantine. It is recommend that these levels be maintained until you become familiar with the operation of your SpamWall and the type and content of the email messages being processed by the system and are able to determine the optimum levels for your particular application and email user base.

You can expect that over time you will adjust these default levels downwards to an optimum setting where a high level of Spam/UCE detection and blocking is achieved with very little chance of any legitimate email messages being blocked or quarantined.

A general example of the optimum Spam Scoring Levels for a SpamWall system in a "production" environment would be as follows:

Tag Level:            2 to 3
Advanced Tag Level:   3.5 to 5
Action/Kill Level::   6 to 10

When setting the Spam Scoring Level values, the lower this number the more sensitive the filter becomes.

The type and content of email messages is widely variable however in general a Spam Score "Action/Kill" level of 6 to 10 should increase the amount of Spam/UCE detected significantly but in most cases is unlikely to produce a significant increase in the number of false positives.

If you and your end users are receiving a significant number of Spam emails being delivered to your email accounts you may decide to adjust your Spam Scoring "Tag" and "Action" levels to more sensitive levels, such as in the 3.5 to 5 range for the "Advanced Tag Level", and the 6 to 10 level for the "Action/Kill Level" where messages scoring above this level are directed to the Spam Quarantine.

If you are seeing only a relatively small number of Spam messages you may decide to maintain your "Advanced Tag Level" at the current default level of "5", or possibly even adjust this value higher, and your "Action" level at the "12" default level or possibly higher. This would depend on the needs and requirements of your particular email user base and the specific type and content of email messages received by your users, and your tolerance with respect to the possibility of having legitimate email messages directed to the Spam Quarantine.

Alternatively, if you are seeing a significant number of legitimate emails being tagged as "SPAM" you may decide to reduce your filter's sensitivity level by increasing the "Advanced Tag Level" level. Likewise, if you are seeing a significant number of legitimate emails being directed the Spam Quarantine you may decide to reduce your filter's "Action/Kill Level" sensitivity by increasing this value.

One thing to note is that the default scoring levels of 1/5/12 and the scoring levels mentioned in this section of the manual are only recommended levels and you may need to do some testing to find the best level for you and your email user base. Some SpamWall admins find that an "Action/Kill Level" of as low as 2 or 3 works for them as most "person to person" type email will score below the "1" level.

However if your users are mainly business users who receive email on a variety of topics or who receive a significant number of newsletters and other "promotional" type email it may not be a good idea to set an Action/Kill Level of as low as 2 or 3. As recommended in this document ion you can adjust the scoring levels downwards at whatever rate you feel is reasonable until you reach an "optimum" level where the most reasonably possible amount of Spam and other unwanted email is blocked or filtered with little or no chance of any false positives.

Another important thing to keep in mind is that all domains and users having their email processed by the system can have access to their own individual Spam Scoring Level settings via the "My Antispam Scoring" screen in their control panel login account if one has been set up for them.

Even though your users may not really need control panel login access to view and manage their quarantined email and other settings in cases where the default system Spam Score settings in particular are not entirely suitable for a particular domain, email user or group of users then there is always the capability available to allocate these users with their own control panel login account so that they can set Spam Scoring levels and make other appropriate adjustments according to their own individual requirements.

The default Spam Scoring Levels set on your SpamWall system are a good overall default configuration for detecting and filtering Spam/UCE and other unwanted email, and your SpamWall system will via it's own auto-learning and auto-tuning mechanisms become more sensitive and adept at the detection and handling of Spam/UCE and other unwanted email over time. Based on your own requirements it may still be a good idea for you experiment with and adjust the sensitivity of your Spam Scoring Levels in order to achieve the best overall level of Spam/UCE detection and management for your particular email user base and the specific type and content of email messages received by your users.


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