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LMi.net SpamAssassin FAQ

1. What is SpamAssassin?
2. How does it work?
3. Where does SpamAssassin come from?
4. How do I use SpamAssassin?
5. How can I customize SpamAssassin?
6. Can't SpamAssassin simply delete the spam instead of just tagging it?
7. Can I write my own rules?
8. Why did you turn off my RBL checks in user_prefs?

SpamAssassin is a mail filtering program that can examine mail arriving in your mailbox, and then alter the subject header making it easy for you to delete, or filter out, incoming spam. We have found that SpamAssassin will correctly detect over 80% of the spam coming into our mail servers.

SpamAssassin can be customized for your specific needs. For example, if you are getting legitimate email tagged as spam, you can instruct SpamAssassin to "whitelist" the address the email is coming from, so it will always pass that email through. You can also raise or lower the threshold it uses to determine if the message is spam or not- the lower the threshold, the more likely a message will be tagged as spam. See below for more instructions on how to do this.

SpamAssassin runs as a runs as procmail filter. It examines the content of each new message you receive, looking for certain characteristics that are typical for spam. For example, does the body of the email contains words like "Mortgage", "Viagra" or "Penis Enlargement" ? If so, then it assigns adds a number to a counter. Once the counter reaches a user-defined threshold, SpamAssassin will tag it as spam, and either change the subject header, or simply delete it.

SpamAssassin is an "open source" project, developed by several people. The software made available free of charge to anyone. We have installed SpamAssassin on our mail servers, and can set it up for any of our customers, free of charge.

Please see the SpamAssassin home page for more information, including complete documentation.

Once we have installed SpamAssassin in your mailbox you will notice that most of the spam you are getting has the string "!!SP" in front of the subject line. You can then create a mail rule, or filter, to automatically delete these messages, or just move them out of your inbox to another folder, for later examination and probable deletion. We actually recommend this latter method, as sometimes SpamAssassin will identify a legitimate email as spam. This can happen with some mailing lists.

Mail rules, or filters, and handled differently with each email client application. For example, if you are using Outlook Express under Windows, you would look in the Tools menu, and then Message Rules->Mail. Click New. The condition you want is "Where the subject line contains specific words". Choose the action you want done (i.e. Delete it). You'll see the phrase "contains specified words" underline below. Click this, and it brings up a window that you can type the word. Enter "!!SP", then click OK.

If you use Eudora (4.2 or later) on a Mac, choose "Make Filter..." from the Special menu. You want to match incoming mail where the Subject contains "!!SP", and then either transfer to another mailbox, or just delete it.

If you need help setting up a message rule in your email software, please contact our technical support dept, and we can assist you.

In order to customize SpamAssassin yourself, you will need access to FTP client software, or else a text editor that can open files via FTP.

We recommend this latter option, as it makes the process much easier. If you use a Macintosh, we recommend TextWrangler from Bare Bones Software (or the more full-featured BBedit...)

For Windows users, try the freeware FileZilla. This is a standard FTP client, but can use any text editor (such as the Windows Notepad) to edit text files from an FTP server.

Once you have the software in place, you need to FTP to "pop.lmi.net". Your username and password is the same as you use for you email. You then need to go into the ".spamassassin" directory inside your home directory and open (or download) the file "user_prefs". This is the file you need to edit in order to customize SpamAssassin.

There are 4 main things you can adjust:

1) required_hits. This is how many "points" an email need to accumulate to be considered spam. The default is 5. If you set this lower, more email will get tagged as spam, but you risk some legitimate mail being tagged incorrectly.

2) whitelist_from. This allows you to specify certain email addresses or domain names that will be exempt from SpamAssassin tagging.

3) blacklist_from. Any email coming from this address or domain name will always be tagged as spam, regardless of content.

4) custom scores. Modifying the default scores applied to certain rules is the best way to make SpamAssassin more effective. For example. if SpamAssassin sees the phrase "Herbal Viagra", it assigns the email .001 points. Not very many, in our opinion. Let's say you are pretty sure that ANY email with that phrase in it is going to spam. You can then tell SpamAssassin to give it 5 points, insuring that it will always be tagged as spam. You do this by adding the line
score HERBAL_VIAGRA 5.0
to the user_prefs file. For more information, see this guide to modifying user_prefs, or the complete list of available tests.

Here is an example of a modified user_prefs file. The comments are in curly braces, and are not actually in the file.

required_hits   4.5	{this overrides the default setting of 5 hits}

whitelist_from  *.lmi.net  {all mail from lmi.net will be allowed in}

blacklist_from *.greatdeals4u.com  {all mail from greatdeals4u.com will be tagged}


{just a few examples of tests that we increased the score on, making it catch more spam}

score VIAGRA 4.0
score HERBAL_VIAGRA 4.5
score NATURAL_VIAGRA 4.5
score VIAGRA_ONLINE 4.5
score VIAGRA_COMBO 4.5
score EJACULATION 4.0
score MORTGAGE_BEST 4.0
score MORTGAGE_PITCH 4.0
score MORTGAGE_RATES 4.0
score PENIS_ENLARGE 4.5
score PENIS_ENLARGE2 4.5
score IMPOTENCE 4.5
score HTML_LINK_CLICK_HERE 3.0
score HTML_LINK_CLICK_CAPS 3.0
score MARKETING_PARTNERS 3.8
score LIMITED_TIME_ONLY 4.0
score OFFERS_ETC 3.5
score CLICK_BELOW 3.0
score CLICK_BELOW_CAPS 3.0
score MIME_HTML_ONLY 3.0
score MISSING_MIMEOLE 3.0
score MISSING_OUTLOOK_NAME 3.0
score REMOVE_PAGE 3.0
score MAILTO_TO_REMOVE 3.5
score HOT_NASTY 4.0
score USER_AGENT_MOZILLA_UA .01
score DO_IT_TODAY 3.5
score SATISFACTION 3.5
score HTML_FONT_BIG 3.0
score MIME_HTML_NO_CHARSET 3.0
score LOW_PAYMENT 3.5
score SUBJ_VIAGRA 3.5
score FREE_CONSULTATION  3.5
score HTML_SHOUTING3 3.0
score HTML_SHOUTING4 3.0
score HTML_SHOUTING5 3.0
score HTML_SHOUTING6 3.0
score RAZOR2_CHECK 2.0
score RAZOR2_CF_RANGE_61_70 3.0
score RAZOR2_CF_RANGE_71_80 3.0
score RAZOR2_CF_RANGE_81_90 3.0
score RAZOR2_CF_RANGE_91_100 3.0
score HTML_WEB_BUGS 3.0
score INVALID_DATE 2.8

Yes! You can instruct SpamAssassin to simply delete the email before you download it. This is especially convenient for dial-up customers who don't want to waste time waiting for spam to download to your computer.

The danger here is that when SpamAssassin deletes an email, you will never see it, and the person that sent it will not know that you never read it. We always recommend using SpamAssassin for a while before you engage this option, so you can be sure none of your legitimate email is being tagged as spam.

Here's how you do it:

First, see question #5 above for info on how to edit text files in your home directory via FTP, then:

1) Edit the .procmailrc file in your home directory (/home/users/username/.procmailrc)

2) You will see the following text:

:0fw
| /usr/local/bin/spamc

:0: 
* ^X-Spam-Status: Yes 
/dev/null 

Here's what a completed file would look like if your username was "joe"

SHELL=/bin/sh

VERBOSE=no
LOGABSTRACT=no
LOGFILE=/home/users/joe/procmail.log
LOCKEXT=.lock

:0fw
| /usr/local/bin/spamc

:0: 
* ^X-Spam-Status: Yes 
/dev/null 

4) Just save the file and you are finished.

We realize that many of you may not ge comfortable editing these configuration files yourself. If so, just send an email to "support@lmi.net" and we can make the changes for you.

No. It's too much of a security risk.

The RBL checks, as used in Spamassassin, are broken. Do not turn them on. Turning them on causes Spamassassin to take 30 seconds to process messages, which is unacceptable.