How to Filter Spam on the Center for Aging Email System
General information on spam filtering
In the interest of giving users more control over filtering
unwanted email messages, the computing staff has installed a program
called SpamAssassin. (http://www.spamassassin.org) This program augments
the headers of incoming email by adding several additional lines. It does
not change the way that email is delivered in any way, but the addition
of these new headers gives users the opportunity to filter their incoming
mail according to their own standards.
These additional headers provide a score for each message, which
estimate the likelihood that this particular piece of email is spam. Below
is an example of what an augmented header looks like:
X-Spam-Flag: YES
X-Spam-Status: Yes, hits=22.6 required=8.0
X-Spam-Level: **********************
SpamAssassin uses several heuristics to determine if a piece of
mail is spam. Typically a value of hits greater than 8.0, as seen in the
X-Spam-Status line, is spam. Accordingly we have set the system-wide
default to be 8.0. This number can be adjusted by each user. You can also
create your own 'white_list' or 'black_list' to accept or reject all
messages from a particular address.
How to filter spam
In order to take advantage of this filtering, you can do one of
several things - mark a message as SPAM in the Subject field, move spam
to a folder or delete the message. We suggest that you start by either
marking the message as spam or moving it to a folder and reviewing the
messages to make sure the filter is working as you expect. Over a period
of time you can 'tweak' the filter by adjusting the numeric threshhold
and creating white lists and black lists. If you become confident that no
legitimate messages are being marked as spam, you can set up your email
program to delete those messages, but be sure this is what you want,
because once the message is deleted, it's gone.
To change the threshhold of number of hits required for a message
to be considered spam:
1. Log on to the UNIX system.
2. Edit the file ~/.spamassassin/user_prefs to add these lines at the end
of the file:
# How many hits before a mail is considered spam.
required_hits 5.0
The first line is a comment. The second line sets the threshhold at 5.0.
Setting up mail clients to filter spam
Netscape Messenger
1. In version 4, do Edit -> Message Filters -> New
In version 6, do Tools -> Message Filters -> New
2. In the Filter Rules window, name the filter X-Spam-Flag
3. Click the 'Advanced...' button
4. In the 'New Message Header' box enter 'X-Spam-Flag' and click Add, then
click OK.
5. When returned to the Filter Rules window, select "Match any of the
following."
6. From the pulldown menu directly above the "More" button, select
X-Spam-Flag.
7. In the field to the right of "Contains", type YES.
8. In the box next to the word "then" choose the action you want to take.
9. Click OK in the Filter Rules window and click OK in the Message Filters
window.
Pine
Start from pine's main menu.
1. Press S for Setup.
2. Press R for Rules; then press F for Filters.
3. Press A for Add.
4. Press Enter/Return, then set the nickname to "Spam Filter". Press
Enter again to save the name.
5. Check the CURRENT FOLDER CONDITIONS BEGIN HERE section. Make sure that
the Specific option is set and the Folder List is "INBOX". If not, make
the required changes so that that is the configuration.
6. Cursor to th section FILTERED MESSAGE CONDITIONS BEGIN HERE and type
'x' for (X)tra header. In the space provided type 'X-Spam-Flag'. Press
Enter. Press 'C' to change the value to 'YES'. Press Enter.
7. Scroll down to 'Message is New?' and type a * on Yes.
8. Scroll down to the ACTIONS BEGIN HERE section. Make sure the 'Filter
Action' option is set to Move. Put the cursor on 'Folder List =' and
hit Enter. Type in the name of the folder where you want to put
possible spam, such as "PossibleSpam" to remind yourself that it could
contain false positives.
9. Press E for Exit Setup; press Y to save the changes; press Y to create
the spam folder.
9. Press E again to Exit Setup and press Y to save.
Eudora
1. Go to the Tools: menu and select Filters to open the Filters window.
2. To add a new filter, click NEW.
3. Select the option to Match Incoming messages.
4. In the 'Header:' field type in X-Spam-Flag.
5. The next drop down field should have the word 'contains'.
6. In the field to the right of the word 'contains' type in YES.
7. Under Action, move the mouse over the arrow next to None and click.
Not all actions are available in the free version of Eudora.
8. Select 'Transfer to' near the bottom of the list. When you do this a
field with the word 'In' will appear.
9. Click on 'In' and select 'New...'
10. Enter Spam for the name of the new mailbox to which your messages
identified as spam will be transferred. Click OK.
For more information, including screen shots, see the following web page:
http://www.eudora.com/techsupport/tutorials/win_filters.html
Outlook 2002
0. On the UNIX system, edit the file ~/.spamassassin/user_prefs to add
these lines at the end of the file:
# Rewrite the Subject: field to identify the message as spam
rewrite_subject 1
1. Select Rules Wizard from the Tools menu.
2. Select your Inbox folder for the "Apply changes to this folder" field.
3. Click the New button.
4. Select "Start from a blank rule".
5. Select "Check messages when they arrive".
6. Click "Next."
7. Checkmark the Condition "with specific words in the subject".
8. Click "specific words" in the Rule description field to edit it.
Type ***SPAM*** in the "Specify words or phrases..." field.
9. Click "Add" and then click "OK".
10. Click "Next."
11. Checkmark "move it to the specified folder" from the "What do you want
to do..." list.
12. Click "Specified" in the Rule description field to edit it.
13. Click "New" to create a new folder.
14. Type 'Spam' in the Name field
15. Click in the "Select where to place the folder" field and click
INBOX then "OK."
16. Click "Finish" to create the rule.
17. Click "OK" to exit.
Outlook Express 6
NOTE: Outlook Express 6 can only filter local folders used by a POP3
protocol connection. If you are using an IMAP protocol connection, you
must use another mail client to filter mail identified as spam by
SpamAssassin.
Please contact Irv Eisen, irv at geri.duke.edu with questions or
to arrange a time to help you set up filtering.
