Anti-Spam Email Procedures at
DU Law School
The
Some of the features of the new device are:
- Uses the collective experience of millions of email users to better identify spam than current methods
- Allows you to choose whether or not to have your mail scanned for spam
- Allows you to choose how aggressively your mail is scanned for spam
- You choose whether messages suspected of being spam are tagged and delivered to your account, or are held on the anti-spam system for your review
- Allows you to "whitelist" email addresses to assure that mail from people you know are received without risk of being blocked
The Device
The anti-spam device is called the Barracuda Spam Firewall 600.
It is a dual processor,
"hardened" Linux-based system running special software designed to check
email for spam and viruses, and to provide an easy-to-use web interface to
allow you to modify your own anti-spam settings, and to process your
"suspected spam" messages. All mail received from the Internet is
first sent to the Spam Firewall which "scores" messages on a scale of
0 through 9 (0=it doesn't think it's spam, 9=it really thinks it's spam), and checks them for viruses, and
then is passes them along to the email system for delivery to your account (if
appropriate).
From your browser click here https://barracuda.law.du.edu
just enter your email address in the Username field and click Create New Password. The Spam
Firewall will send you an email message containing a newly generated password
which you can then use to log in and set to one of your own choosing.
How it works
about once per day, you will receive an email from "Sturm College of Law
Spam Firewall" containing a report of quarantined email messages sent to
you that have been classified as suspected spam by the firewall, and have been
blocked from delivery to your Exchange mailbox. (NOTE: If you have not received
any messages that have been quarantined as suspected spam, you will NOT receive a report.) a report will look like this below.
You can judge whether or not a message is
spam by looking at who the message is From, and at the Subject as shown on the report. If
you only have a few messages to review and process, you can just click Deliver, Whitelist, or Delete as you see fit using the
links under the Actions
column of the report. If you have a lot of messages to review and process, or
if you want to change the way the system processes your mail, you can click the
"click here"
link at the bottom of the report. This will log you directly onto the system
via a web browser.
Once logged on processing large numbers of
messages more efficient is that you can use the checkboxes to the left of the
screen to select many messages and then process them all with the single click of the
Deliver, Whitelist,
Delete,
Classify as Not Spam,
or Classify as Spam
buttons above the report headings. What
the buttons do:
|
Deliver |
Delivers message to your
mailbox, removes it from quarantine. |
|
White list |
Delivers message to your
mailbox, removes it from quarantine, and adds the sender's email address to
your "white list" so that future messages from this address will not be categorized as spam again. |
|
Delete |
Deletes the message
without sending it through to your mailbox |
|
Classify
as Not Spam |
Delivers message to your
mailbox, removes it from quarantine, and helps "train" the firewall
that this kind of message is not spam.* |
|
Classify
as Spam |
Deletes the message
without sending it through to your mailbox and helps "train" the
firewall that this kind of message is spam.* |
|
|
A copy of the message is
uploaded to the firewall vendor, Barracuda Networks, so that their anti-spam
definitions can be updated to help block this type of message in the future. |
Taking control
By default, the Spam Firewall will filter your email
using settings and preferences set up for you by Sturm College of Law Networking
Services Dept. You may find the default settings too "aggressive"
(the system classifies too much "good" mail as spam), or too weak
(too much spam still gets through). No filtering system can decide perfectly
what you would
consider to be spam, and what you would not. However, you now have some control
over the process! When logged onto the system as shown above, you can modify
how the system processes your mail by selecting the "PREFERENCES" tab along the top.
The
“PREFERENCES” Tab (Whitelist/BlackList) Screen
On the Whitelist/Blacklist
screen, you can add email addresses of people whose email you never want to
have filtered by the Spam Firewall by adding them to the Allowed Email Addresses and Domains whitelist. (Addresses are also added here if you click the Whitelist
button as described earlier.) You can also block all email from a specific
address by adding it to the Blocked
Email Addresses and Domains blacklist.
The “PREFERENCES” Tab (Quarantine Settings) Screen
If you want to turn off
blocking of suspected spam, just set Enable
Quarantine to "No"
and click the Save Changes
button (I DO NOT RECOMMEND THIS).
You can turn it back on again anytime you like. When Quarantine is disabled, messages
suspected of being spam are sent along to your mailbox anyway, with the subject
line modified to contain the phrase "[QUAR]" at the beginning. When Quarantine is
enabled, the messages are held on the Spam Firewall to be processed as explained
above.
Don't want your mail checked
for spam? Or, do you want to change the threshold of "spam-score"
that the system uses when scanning your mail? Click the Spam Settings button along the top.
(The current default settings are Tag Score: 3.5, Quarantine Score: 10 (disabled), and Block Score: 6.)
If you don't want your mail
scanned for spam at all -- perhaps you're having difficulty receiving a
legitimate message from someone, or don't like the idea of having a machine
sort through your mail -- just set Enable
Spam Filtering to "No"
and click the Save Changes
button.
Want to change the thresholds
at which the system classifies a message as spam? Set Use System Defaults to "No" and change your settings as
described below.
The system assigns a "spam
score" to each message it examines using several methods including,
blocked network addresses, messages originating from known spam senders,
messages containing spam-like "fingerprints" (as reported by you and
other users with the Classify
as Spam button described
earlier), intention analysis, Bayesian analysis, and rules (banned phrases and
attachments). The score can range from "0" (system does not think the
message is spam at all) to "9" (system really thinks the message is
spam). You can control what the system does with the message, depending on how
high the message's score is. In the example shown above, the Tag score is 3.5,
and the Quarantine score
is 7. This means that any message whose score is below 3.5 will be forwarded to
your mailbox as usual. Any message with a score between 2.5 and 3.5 will be
"tagged" -- its subject line will be modified to start with "[SPAM?]" and forwarded to your
mailbox as usual. Any message whose score is between the Quarantine score and the Block score will be quarantined as
you specified -- either held on the firewall awaiting your decision about what
to do with it, or passed along to your mailbox tagged with "[QUAR]" added to the subject
line (if you've disabled quarantine). Any message with a score of 9 or higher
will simply be bounced back to the sender without your ever having to deal with
it.
NOTE: Quarantined files have a retention policy set for
30 Days after which they will be deleted.
Note: Even though the Tag, Quarantine, and Block
scores appear to have
"sliders" next to them, they are simply a visual representation of
your settings - you can't slide them. To change a score, enter it in the box
(it may contain a decimal) and click Save
Changes.
Note: You can disable the quarantine function by setting
the Quarantine score
to 10.
Note: If you don't want any chance of blocking a message
based on its spam score, set the Block
score to 10.
When you are done working on your Spam firewall account, you should click the "Log Off" link in the upper right corner of the web page.
Want to change your Spam Firewall password?
Click the Password
tab button along the top
The “PREFERENCES” Tab (Password) Screen
If you'd like to check your Spam Firewall
quarantine without waiting for your daily quarantine report email message, you
can log in using the password sent to you by the firewall. The automatically
generated password is usually your email name followed by several random
characters. You can change it to something more memorable (perhaps set it the
same as your email password?) by filling out the screen above and clicking Save Password.
Don't know your password? Just go to the
Spam Firewall's login page at https://barracuda.law.du.edu
Important Notes
- You should log onto the Spam Firewall at least once every few days
and process any messages held in quarantine. Messages left in quarantine
longer than 30 days may be deleted and are not recoverable. If you do not
wish to process your quarantine folder, please disable quarantine for your
accounts as described above so that messages do not build up on the
firewall.
- The
- Please bear with us as we make adjustments to the new system. As
with any new system, there may be issues we will need to resolve along the
way!
- Note that no anti-spam mechanism is perfect. If you do not like
the way the system works, you can opt out of it, or adjust its behavior,
as described in this document.
- If you have questions about the system, please contact the Law
School Help desk x16464, email jpope@law.du.edu
or drop by the Help Desk office #265.
Anti-spam FAQ’s
System Requirements
What
are the minimum system requirements to use Anti-spam technology on my Personal
Computer?
None, it is a network-based system that requires no additional
processing on personal computers.
Will
it work with both Mac’s & PC’s?
Yes. Although PC users will have the ease of classifying spam from
their outlook tool bar using an outlook plug-in while MAC users will
always have to use the web interface.
Whitelist/Blacklist
What is a Whitelist?
To place an e-mail address or
domain on a list of items that is deemed spam- or virus-free.
What is a Blacklist?
Generally, a blacklist is a list
of people or things that have incurred disapproval or suspicion or are to be
boycotted or otherwise penalized. Related to e-mail, blacklisted IP addresses
will not be allowed to send mail to someone trusting the blacklist. Blacklisted
e-mail addresses will not be allowed to send mail to a user or organization
Is categorizing emails as spam/not-spam the same as whitelist/blacklist?
No. Classifying your emails
using the outlook plug-in (red/green envelop button) or using the web interface
is not same as whitelist/blacklist. Whitelist/blacklist data is based on source email address
or domain while classification data from the spam/not-spam marking is used in Bayesian scorning
Bayesian Learning
Bayesian Learning constitutes a probabilistic view of
learning, based on Bayes Theorem. The underlying assumption is, that
there is a set of hypotheses, each having a certain probability of being
correct. Receiving more information changes the probabilities from a learner's
point of view. For instance an observation might contradict a hypothesis, or
strengthen the belief in it. The aim in this setting is to be able to find a
hypothesis with highest probability of being correct, given a specific set of
data / piece of information. The more emails are classified (spam & not
spam) the more accurate spam scoring becomes.
