SAN JOSE IBM PC CLUB - SPAM PREVENTION TOOLS

Tools Utilized

The sjpc.org mail server is using 4 spam-prevention tools:
1.  Locally maintained list of senders to block
2.  Centrally maintained list of known spammer addresses
3.  Centrally maintained list of open relay points
4.  SpamAssassin to examine the text of the message for indicators of spam
Items 1, 2, and 3 enable our server to refuse all mail from known spam addresses, and item 2, 3, and 4 will place spam mail in the user's spam folder.

It is important to note that there is no spam checking or a spam folder if you have the postmaster forward your SJPC mail to another account instead of storing it locally.  The mail transfer agent (sendmail) forwards mail without passing it on to the local mail delivery agent (procmail).  It is Procmail that calls SpamAssassin, so SpamAssassin doesn't see forwarded mail.

Spam Folder Contents

Messages that SpamAssassin determines to be spam messages are placed in your spam folder which is similar to a Windows file without a file extension such as .txt.  These messages will remain in the spam folder unless the folder size exceeds 2 MB.  At the end of each month, a check is run on spam folder sizes, and any spam folder that exceeds 2 MB is deleted.  There is no time criterion on deleting the spam folder.  After you have reviewed the content of the spam folder, you can delete it, and a new spam folder will be generated by SpamAssassin when it is needed for new spam messages.  Deleting the spam folder after checking the messages makes it easier to review new messages.

Reporting Spam

SpamAssassin analyzes message headers, subject, and text to identify junk mail.  Spam filtering is not an exact science, so we need your feedback on spams that got through as false positives.  If a spammer is able to slip something through without being tagged, please let us know so we can tune the spam filter.  Turn on ALL HEADERS for the message, then forward it to abuse@sjpc.org with "Spam message" in the subject line.

Viewing the Spam Folder

To view your spam folder using your browser, key the following in the command line where "userid" is your SJPC assigned user name and "password" is your SJPC password.

Internet Explorer:  ftp://userid:password@sjpc.org/mail/spam

You can also view your spam folder using DOS command prompt FTP or an applications such as WS FTP-LE and WinSCP.  Information on using these can be found by going to the help index at http://www.sjpc.org/internet/helpindex.htm under the Web Hosting section.  Make sure you use home/userid/mail rather that home/userid/public_html so that you reference the directory containing the spam folder instead of your web site directory.

Deleting the Spam Folder

Internet Explorer, DOS command prompt FTP, WS FTP-LE, and WinSCP can be used to delete the spam folder in the directory at home/userid/mail.  Information on deleting can be found by going to the help index at http://www.sjpc.org/internet/helpindex.htm under the Web Hosting section.
.
Adding Unblocking Entries to User Preferences

If you find a  message from a mailing list to which you subscribe that is tagged as spam, you can update your own user preferences in the user_prefs file in the /home/userid/.spamassassin directory (note the dot).  There are comment lines in the user_prefs file that begin with "#" which contain more information about unblocking.  An example of an unblocking entry placed at the end of the user_pref  file to unblock mail from a.xyz.com and b.xyz.com is as follows.
whitelist_from  *.xyz.com

Changing Your User Preferences

 Since these files are hidden Internet Explorer and WS FTP-LE do not see them.  WinSCP is a file transfer program that shows hidden files.  DOS command prompt FTP doesn't list hidden files, but it will allow you to use the change directory command
cd home/userid/.spamassassin (note the dot) to download, modify, and upload the user_prefs file.  Information on WinSCP and DOS command prompt FTP can be found by going to the help index at http://www.sjpc.org/internet/helpindex.htm under the Web Hosting section.  Make sure you use home/userid/.spamassassin/ as the directory rather that home/userid/public_html so that you reference the directory containing the user_prefs file instead of your web site directory.

Procedure to Update User Preferences Using WinSCP

1.  Launch WinSCP, and click Login.

2.  Double click the .spamassassin folder, and the directory with the user_prefs file will appear.

3.  Right click on the user_prefs file, click Edit, and a copying window will appear while the file is being copied to a temporary file which will be deleted after the editor is closed.

4.  When the notepad like dialog box appears, you can modify the text file.

5.  Click the Save icon which is the second from the left in the command line, and the copying window will appear while the modified file is being saved on the remote server.

6.  Close the dialog box and close WinSCP.

Procedure to Update User Preferences Using Command Prompt FTP

1.  Click Start, click Programs (All Programs for XP), click Accessories, and click  MS-DOS Prompt (Command Prompt for XP).

2.  Change the directory to specify the folder in which you want to download the user_prefs file for updating.  For example cd c:\"my documents"  The server will reply
C:\My Documents>

3.  Enter ftp www.sjpc.org.  The server will reply
Connected to www.sjpc.org.
220 sjpc.sjpc.org FTP server ready.
User (www.sjpc.org:(none)):

4.  Type your userid and press the Enter key..  When prompted, type your password and press the Enter key.  The server will reply
230 User logged in.
ftp>

5.  Change the directory to  /home/username/.spamassassin which is where you want to get your file.  You are logged into the /home/username directory.  To change directories, enter cd .spamassassin (note the dot)  The server will reply
250 CWD command successful

6.  To verify that you are in the right directory, enter pwd.  The server will reply
ftp> pwd
257 "/home/username/.spamassassin" is current directory.
ftp>

7.  To download user_prefs from the server to the directory (folder) you specified, enter get user_prefs and the server will reply (Note that bytes, seconds, and Kbytes/sec will vary)
ftp> get user_prefs
200 PORT command successful.
150 Opening ASCII mode data connection for user_prefs (1674 bytes).
226 Transfer complete.
ftp: 1704 bytes received in 1.32Seconds 1.29Kbytes/sec.
ftp>

8.  Rename the user_prefs file that you downloaded to user_prefs.txt, open it as a text file, modify the file,  and rename the file back to user_prefs.  If you prefer, you can force the file to open as user_prefs by specifying "Notepad" as the file with which to open it.

9.  To upload the user_prefs file to the server, enter put user_prefs  The server will reply (Note that bytes, seconds, and Kbytes/sec will vary)
ftp> put user_prefs
200 PORT command successful.
150 Opening ASCII mode data connection for index.htm
226 Transfer complete.
ftp: 1674 bytes sent in 1.00 Seconds 8000.00 Kbytes/sec.
ftp>

10.  To end the session and terminate the FTP program, enter the close command followed by the quit command.


Return to the San Jose IBM PC Club's home page