Spam Control Facilities
We use Clam-AV to block viruses. Mail containing viruses is rejected with a message sent back to the sender specifying the infecting virus.
Clam-AV won’t catch all viruses. Between the time a virus is released into the wild and the time it is detected, analysed, and a signature created, that virus is undetectable. We recommend that you install an anti-virus program on your computer, especially if using Windows.
Message which clear Clam-AV are then scored by SpamAssassin according to the likelihood they are spam.
If you do not have Procmail rules, system rules will place mail scored as spam in your “spam” folder.
If you have Procmail rules, then your rules to decide what to do with mail scored as spam. Please see System Procmail Rules.
Bayesian Filtering – Training
SpamAssassin includes Bayesian filtering. Bayesian filters learn from examples of what is spam and what is ham (non-spam).
Please send spam to email@example.com.
Please send non-spam (ham) to firstname.lastname@example.org. Mail sent to hamtrap must be sent from an eskimo address.
Bayesian filters work best if they have lots of material to compare. Please help with effective training by sending non-spam to hamtrap even if it is not misclassified. Without some ham to compare to spam, the filters can not distinguish between spam and ham.
It is best to use Pine or other mail programs which contain a “bounce” facility that will send the message without adding additional headers. Otherwise, SpamAssasin’s Bayesian filtering may decide that anything you originate and send to other users here is spam.
It is best to send ham (non-spam) to hamtrap after sending spam to spamtrap, as it will allow the Bayesian filters to “unlearn” anything incorrectly learned as spam.
SpamAssassin can be tailored to your preferences. In your “$HOME” directory, there is a hidden directory called “.spamassassin” that will contain a file called “user_prefs“.
The “user_prefs” file is where you can override any system defaults, set the scoring for the spam threshold as low or high as you like, change the scoring of any individual rules, and white_list or black_list any addresses or domains you wish.
The “user_prefs” file is an text file. You can edit it with any text editor, pico, nano, ex, vi, emacs, etc. Anything after a ‘”#” is a comment. There are commented examples in the file of how to do most things.
whitelist_from email@example.com #whitelist a specific address. whitelist_from *@domain.com #whitelist an entire domain.
blacklist_from firstname.lastname@example.org #blacklist a specific address. blacklist_from *@domain.com #blacklist an entire domain.
By default, customers can receive mail at four addresses, email@example.com, firstname.lastname@example.org, email@example.com, and firstname.lastname@example.org. Ola Grande customers can also receive e-mail at email@example.com.
Because eskimo.com has been around the longest, it is more prone to receiving spam than the other addresses. Some customers use eskimo.net for their primary e-mail address. If you wanted to block all e-mail except your eskimo.net address, you could so so with the following rules:
blacklist_to *@eskimo.com blacklist_to *@eskimonorth.com blacklist_to *@eskimonorth.net
You can adjust the score required for mail to be considered spam. Higher scores increase the likelihood spam will end up in your INBOX. Lower scores increase the likelihood legitimate mail will be placed in your spam folder. “5” is the default value.
You can set how much a rule contributes to the spam score. A score of zero disables that test. Negative scores reduce the likelihood mail will be considered spam.
Speakers of Asian languages, like Chinese, Japanese, and Korean, will want to add or uncomment the following:
score HTML_COMMENT_BBITS 0 score UPPERCASE_25_50 0 score UPPERCASE_50_75 0 score UPPERCASE_75_100 0 score OBSCURED_EMAIL 0
Speakers of any language that uses non-English accented characters may wish to add or uncomment the following line. These turn off rules that fire on misformatted messages generated by common mail apps in contravention of the email RFCs.
score SUBJ_ILLEGAL_CHARS 0
For a complete list of SpamAssassin tests, please see http://spamassassin.apache.org/tests_3_3_x.html.