Netrack utilizes at least 5 different levels of anti-spam and
anti-virus controls. Approximately 95% of all incoming spam and
virus messages are halted by these controls. These controls are
not based on the content of the message. The remaining 5% are
tagged as likely to be spam based on content. This tagging can
be customized by each user.
Netrack uses SpamAssassin
as a mail content filter.
This tool is completely customizable by and for each user.
These instructions tell you how to filter email, disable
spamassasin, customize the tagging, and delete spam on the mail
server. If this information is a bit too daunting for you, call
Netrack and we'll be happy to customize the filters to your individual
specifications.
SpamAssassin provides a means to tag messages that are believed
to be spam, or "unsolicited commercial e-mail" (UCE).
The default configuration provides the following tags in your e-mail
message headers for those messages believed to be UCE. Most notably
"UCE:" is prepended to the subject line of any message
that is probably spam. The tags are an example of all the headers
added or modified in your mail messages.
Subject: UCE: Great deals on toner
X-Spam-Status: Yes, hits=6.2 required=6.0
tests=CARRIAGE_RETURNS,MISSING_MIMEOLE,
MISSING_OUTLOOK_NAME,SPAM_PHRASE_00_01
version=3.1.7
X-Spam-Flag: YES
X-Spam-Report: 6.20 hits, 6 required;
* 0.6 --
BODY: Spam phrases score is 00 to 01 (low)
* 1.3 -- RAW:
Message contains a lot of ^M characters
* 1.6 --
Message has X-MSMail-Priority, but no X-MimeOLE
* 2.7 --
Message looks like Outlook, but isn't
X-Spam-Level: ******
X-Spam-Checker-Version: SpamAssassin 3.1.7 (2006-10-05)
Please refer to your mail reader program, such as Outlook or Eudora, for
information on how you can sort or filter your incoming mail based on these
header tags.
If you do not want your mail checked for spam, you can disable it on your
account using the following procedure:
Use an FTP program to connect to cybox.com and login with your mailbox
username and password. Then enter the commands as shown in the example below.
The text in bold type is text that you enter.
> ftp cybox.com
Connected to cybox.com.
220 ProFTPD 1.2.4 Server (ProFTPD) [cybox.com]
Name (localhost:barb): barb
331 Password required for barb.
Password:
230 User barb logged in.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> delete .procmailrc
250 DELE command successful.
ftp> bye
221 Goodbye.
SpamAssassin can be customized to tune detection of spam for your specific
needs. For example, SpamAssassin may incorrectly tag some of your mail as
spam when it is not.
SpamAssassin assigns a score to each of your messages based on whether the
message contains certain elements typically contained in spam messages. The
resulting score is compared against a threshold. If the score is above the
threshold, the message is tagged as spam. If the score is below the
threshold, the message is not tagged as spam. The default threshold is 6. If
generally too many messages you receiving are mistakenly identified as spam,
simply adjust the threshold to a higher number. This will also have the
effect of not tagging some spam message as spam.
SpamAssassin can also be configured to always allow messages from or to a
particular email address, hostname, or domain name. This is called a "whitelist."
For example, if you receive product announcements from intuit.com and you never
want them to be considered spam, you would add intuit.com to your whitelist.
For more advanced customization features, see the
SpamAssassin documentation.
To customize the SpamAssassin threshold or manage your whitelist, you will
download a preferences file, edit it, and upload it again. You can use the
following procedure. The text in bold type is text that you enter.
1. Download the SpamAssassin preferences file using an FTP program, following
the example below.
> ftp cybox.com
220 ProFTPD 1.2.4 Server (ProFTPD) [cybox.com]
Name (localhost:barb): barb
331 Password required for barb.
Password:
230 User barb logged in.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> cd .spamassassin
250 CWD command successful.
ftp> get user_prefs
local: user_prefs remote: user_prefs
200 PORT command successful.
150 Opening BINARY mode data connection
for user_prefs (772 bytes).
226 Transfer complete.
772 bytes received in 0.0301 secs (25 Kbytes/sec)
ftp> bye
221 Goodbye.
2. Use any file editor to edit the file called "user_prefs" that you just
downloaded. There are comments in the file to guide you. To adjust the
threshold, remove the "#" character from the beginning of the line containing "required_hits"
and set the number to the threshold you want. For example,
required_hits 8
To add email addresses, hostnames, or domain names to your whitelist, put
each on a line beginning with "whitelist_from" or "whitelist_to". "whitelist_from" takes a second argument to check on the Received lines. In this example, if the from address indicated intuit.com, but it came from a computer not at intuit.com, it won't be whitelisted. For example,
whitelist_from *intuit.com intuit.com
whitelist_to my-friends-list@yahoogroups.com
3. Upload the modified "user_prefs" file back to
the cybox server using an FTP program, following the example below.
> ftp cybox.com
220 ProFTPD 1.2.4 Server (ProFTPD) [cybox.com]
Name (localhost:barb): barb
331 Password required for barb.
Password:
230 User barb logged in.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> cd .spamassassin
250 CWD command successful.
ftp> put user_prefs
local: user_prefs remote: user_prefs
200 PORT command successful.
150 Opening BINARY mode data connection for user_prefs.
226 Transfer complete.
772 bytes sent in 0.018 secs (42 Kbytes/sec)
ftp> bye
221 Goodbye.
When and if you are confident that your customizations are identifying only
spam and not mail that you want, you may tell the cybox server to delete it
automatically. That way you don't have to download it to your mail
program. You may also have SpamAssassin tag messages at one threshold and
delete
messages at another threshold. For example, maybe a threshold of 7 hits works
pretty well for you. But every now and then, a real message has a score of 7 or
8. You can tag spam at the threshold of 7, and delete messages at a score of 10
or 15 or higher.
To have the server delete your spam, download the .procmailrc
file, edit it, and upload it again. Use the instructions in the
"Customizing SpamAssassin" section to download and upload,
but don't do the "cd" command and substitute
.procmailrc for user_prefs in the
"get" and "put" commands.
Edit the file and remove the "#" character from the bottom
three lines of the .procmailrc file.
Set the number of stars in the "Spam-Level" line to correspond to
the threshold for deleting messages. For example, if you want to
delete all spam messages with a score of ten or higher, the last
three lines of your .procmailrc should
look like this:
:0H
* ^X-Spam-Level: \*\*\*\*\*\*\*\*\*\*
/dev/null
Please contact Netrack if you have any questions or difficulties using
SpamAssassin.
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