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Using E-Mail Filters to Control Spam

About Drake's SPAM service

The Office of Information Technology has implemented PureMessage, a service that will help each of us manage the problem of unsolicited bulk e-mail, commonly called spam. PureMessage computes a spam probability for each message coming from the Internet, based upon the characteristics of its headers and content. If the computed "spam probability" for a given message is greater than 20%, PureMessage adds a custom header, called "X-PerlMx-Spam", that communicates its probability estimate. You may already have noticed this in some of the messages you have received, just after the familiar "To:", "From:","Subject:", and "Date:" headers. An example of this header and its contents is:

X-PerlMx-Spam: Gauge=XXXXXXXIIIIIII, Probability=77%

This spam tagging service makes it possible for you to set up message filters on your IMAP e-mail client that will transfer suspect messages out of your INBOX to other folders (sidelining) for later examination and deletion. For example, if you were to set up a filter that would search for "Gauge=XX" in the X-PerlMx-Spam header, messages with 20% chance or better of being spam would be selected. Similarly, header contents of "Gauge=XXXXX" would select messages that have a spam probability of 50% or greater. One could set up multiple headers, sidelining the messages into different folders based upon the spam probability. It is suggested that you initially set up a simple filtering scheme which you may fine tune as you gain experience with how the system works.

Just how effective will this new service be in ridding your INBOX of spam? As you might suspect, the spam assessment process is not fool proof. Preliminary experience has shown that, while it rarely misses a spam message, PureMessage does incorrectly rate some of the messages you are likely to want. Typical of these false alarms are bulk e-mail that you have opted to receive, such as messages from professional organizations, book clubs and airlines. Occasionally, a message sent by a known correspondent will earn a spam rating, simply because of the sender's choice of subject, case, letter spacing, font, color, phrases or use of html. So as not to lose any desireable messages, you should carefully examine the "From:" and "Subject:" columns of the messages that have been sidelined to a separate spam folder.

IMPORTANT!
Remember to check routinely the folder where you have sidelined messages. There may be some messages that you want and must deal with on a timely basis.

The process for setting up filters depends upon the e-mail client that you use. Following are instructions for setting up simple filters using Webmail, Microsoft Outlook, Microsoft Entourage and Apple Mail. Filters would need to be set up for both office and home computers on which you are running a desktop client, such as Outlook or Mail since the filter is stored on the computer where the application resides. Setting up a filter in Webmail need only be set up once, since it would reside on the mail server.

The terms Filter and Rule are used interchangeably for the purpose of these instructions.

Set up a filter in Webmail:

  1. Click the Filters button 
    You will see 2 existing filters, blacklist and whitelist. The whitelist is for email addresses you always want to receive mail from and blacklist is just the opposite. You also have a button here to create a new, personalized filter.
  2. Click New Rule
  3. Give the Rule a name
  4. From the drop down, choose the appropriate criteria (from, to, subject, etc.)
  5. From the next drop down, choose either contains or does not contain
  6. In the last field, enter in a partial address if you've chosen to filter by from, or a partial subject line if you've chosen to filter by subject, etc.
  7. From the next drop down, choose the appropriate action, most likely, 'Deliver to folder' and then choose the folder.
  8. Click Save and you will see your newly created rule in the list

A flash formatted video walking you through the above steps.

Set up a filter in Microsoft Entourage (Macintosh):

  1. Click on the Tools menu > Rules
    Be sure you have 'Mail' (IMAP) chosen rather than POP
  2. Click New
  3. Give the Rule a name
  4. Choose the appropriate for the "if"
  5. Choose the appropriate actions for the "then"
  6. Click OK and you will see your newly created rule in the list

Video coming soon...

Set up a filter in Microsoft Outlook (Windows):

  1. Click on the Tools menu > Rules and Alerts
  2. Click the New Rule button
  3. Choose 'start creating a rule from a template' and click Next
  4. Under Step 1, choose the appropriate conditions
  5. Under Step 2, click the underlined words to edit specifics of actions
  6. Click Next
  7. Verify the conditions and click Next
  8. Verify the actions and click Next
  9. Choose any exceptions if you'd like, click Next
  10. Name the Rule and click Save

Video coming soon...

Set up a filter in Apple Mail (Macintosh):

  1. Click on the Mail menu > Preferences
  2. Click on Rules
  3. Click the Add Rule button
  4. Give the Rule a name
  5. Choose the appropriate criteria for the "if"
  6. Choose the appropriate actions for the "then"
  7. Click OK and you will see your newly created rule in the list.

Video coming soon...

Set up a filter in Microsoft Outlook Express (Windows):

  1. Click on the Tools menu > Message Rules > Mail
  2. Choose appropriate conditions, or 'if'
  3. Choose appropriate actions, or 'then'
  4. Under Rule Description, click on the fields to edit the specifics of the conditions and actions
  5. Name the Rule
  6. Click OK
  7. Click OK

Video coming soon...

Set up a filter in Eudora (Windows and Macintosh):

  1. Click on the Tools menu > Filters
  2. Click New (at the bottom of the screen)
  3. Choose appropriate conditions under Match
  4. Choose appropriate actions under Action
  5. Close the filters window and click Yes when asked to save changes