Skip Navigation
 Search | Directories | Reference Tools
UW Home > UWIN > Computing and Networking > Email 

Junk email (spam) filtering at the UW

Topics on this page

How to filter out junk email

For email accounts on the UW's central email services, the Junk Email (Spam) Filter is on by default. You can change your filter settings by taking the following steps:

With the Junk Email Filter on, email with a score higher than your chosen threshold will be placed in a folder named "junk-mail".

You can turn Junk Email Filtering on or off at any time.

Important: Check your junk-mail folder regularly (at least once a week). Some good messages may get mixed in with the junk, especially if you choose a low threshold or if you like to receive commercially oriented email. You must move such messages to other folders within a week after their arrival or they will be automatically deleted along with the junk messages. If you are not sure where your junk-mail folder is see Finding Your junk-mail Folder

Things to consider

Only for UW central email

The Junk Mail Filter function only works on email handled by the UW's central email services. At present, only email addressed to the following domains can be filtered:

Some departments and centers run their own email systems independent of the central email services. Messages going directly to such systems are not affected by this function.

Forwarded email not filtered

If you forward email addressed to any of the above domains to some other address, it will not be filtered. The filtering only works if you are reading your email from the central email servers.

Email from known high-volume sources of spam may be blocked before it even enters the UW email system. See the Blocking of Email From Some Domains page for more information.

Junk Email Filtering and Vacation Message interactions

If you want both the Junk Email Filtering and Vacation Message functions running at the same time, you should raise your spam threshold to a high value (the High setting).

When the Junk Mail function and the Vacation Message function are on at the same time the spam filtering will happen first. This means the vacation message will only be sent in response to messages that get past the junk email filter. This is good since responding to junk email often just produces more junk email. However, consider the following points:

Not a good idea for POP email programs

Most people at the UW use email programs that read messages directly from the central email servers using a technique called IMAP. Some people, however, prefer another method, called POP, which usually uploads your entire Inbox to to your local computer when you first connect to the email server.

While the Junk Email function may seem to work when you use a POP email program, it is not recommended because such email programs often do not give you a simple way to check your junk-mail folder for any good messages you might want to save.

If you still prefer to use a POP email program and the Junk Email function, the suggested solution is to set your threshold to a high value, thus minimizing the chances that good email will get into the junk-mail folder.

How the Junk Email function works

A two step process

Junk email filtering is a two step process. Each incoming message is given a "spam score" and then either placed in your Inbox (if it has a score below your spam threshold) or placed in a junk-mail folder (if it has score higher than your spam threshold). You choose the spam score threshold value in the EDM.

Messages arrive and are given a spam score When messages arrive at the UW, they are scanned with a system called PureMessage  and given a "spam score" ranging between 0 (probably not spam) and 100 (almost certain to be spam). The spam score is added to the message in a special line in the message header. This line is usually not shown, but with most email programs you can see it if you want to.
Each message contains a spam score The message then goes to the email servers.
Messages with high spam scores go into your junk-mail folder
  • If you have spam filtering turned off, the message simply goes into your Inbox folder (or some other folder if you have other email filters set up).
  • If you have spam filtering turned on, any message with a spam score higher than your chosen spam threshold is placed in a special email folder named "junk-mail". Any messages in the junk-mail folder that are older than seven days are automatically DELETED.

Identifying junk email

PureMessage looks for message characteristics that are common to spam messages, including the following:

The scoring system is regularly updated by PureMessage to improve its effectiveness and deal with changes in the characteristics of junk email over time.

Many aspects of the message are considered in coming up with the final spam score. In practice, the scoring system has been found to be quite effective at identifying what most people consider to be junk email.

Still, just because a message looks like spam to PureMessage does not mean that it is spam. You may choose to receive marketing email messages from a company you purchased a new computer or a book from, for example. Also, some responsible organizations you may want to hear from use the same email distribution programs as spammers or might like formatting their messages in spam-like ways. To be sure that you do not lose messages you want, it is important to regularly check your junk-mail folder once you turn on spam filtering. Any message in your junk-mail folder that is more than seven days old will be automatically and permanently deleted!

Viewing the spam score of a message

When PureMessage decides a message looks like junk email, it adds a line to the message header. With most email programs, this small change will not be evident when you view the message because they usually show only a few header lines, like Date:, To:, From: and Subject:.

If you would like to see the header line containing the spam score, you'll need to have your email client program display the full details of the message headers. How that is done depends on which email client you use. If you need assistance, consult this list of instructions for common email programs. For example, with Outlook Express click the "File" menu, click "Properties", click the "Details" tab,  and click "Message Source."

Here is an example of what you might find:

 X-Uwash-Spam: Gauge=XXXXXXIIIIII, Probability=66%,
  Report="MAILTO_TO_SPAM_ADDR, NO_MX_FOR_FROM, ONLY_COST, RAZOR2_CHECK,
  SPAM_PHRASE_02_03, SUPERLONG_LINE"

The spam score is indicated by the "Probability=66%". The "Guage" attribute is a sort of Roman numeral representation of the spam score which can be handy to use for comparisons in setting up filter rules. The "Report" attribute lists keywords for the message characteristics that determined the spam score. Some characteristics are good (characteristic of messages that are not spam) and some are bad (common to messages people consider to be spam). The score is an expression of the aggregate of all the relevant characteristics.

Frequently asked questions

I can't find my junk-mail folder!

A desktop email program like Outlook Express, Mozilla Mail, or PC-Pine may not show the junk-mail folder for a number of reasons:

  • The list of available folders may need to be "refreshed". That is, the email program has an out-of-date list of what folders are available. Usually, email programs have a "reset" or "refresh" command.
  • Many email programs have the ability to hide or show folders so that the list of folders you see is not the complete list of folders available on the email server.
  • Your email program may be improperly configured so that it is looking in the wrong location for the folders. Detailed instructions for obtaining and configuring email programs for use with the UW central email system can be found on the Getting and Setting Up Email Programs page.

For example, Windows Outlook Express has the ability to hide or show folders. In most cases where a Windows OE user cannnot find their junk-mail folder, the folder is just hidden. You can make it appear in your UW Internet Mail folder by taking the following steps:

  1. Pull down the "Tools" menu to "IMAP Folders." A pop-up box will appear.
  2. In the pop-up box, click on the "Visible" tab. This will display the list of folders currently visible (not hidden). Scroll down the list and see if "junk-mail" is on that list.
    1. If "junk-mail" does show in the "Visible" list, go on to the next step
    2. If "junk-mail" does not show in the "Visible" list, click on the "All" tab and scroll down to "junk-mail". Click once on "junk-mail" and then click the "Show" button. A little envelope icon should appear next to "junk-mail".
  3. To see all your visible folders look in your "Folders" window, which is usually located to the left of the main window, unless you have the "Folders" window closed.
    1. If the "Folders" window is not showing, look just below the "Create Mail" button and you will see the words "Outlook Express" followed by a little triangle pointing down. Click on the words and a pull-down list of all your folders will appear. To get it to stay down, click on the little stick pin in the upper right corner of the folder menu pull-down list. In that list should be a folder named "UW Internet Mail" (or in some cases a name like "uw_netid.deskmail.washington.edu"). In the list below that folder should appear "junk-mail"
  4. To view the messages in any of the folders in the folder list, just click on the name of the folder.  
    • The folders under "Local Folders" are located on your computer.
    • The folders under "UW Internet Mail" are located on the central UW email servers.
       
What difference does the sequence of filtering make?

The sequence of filtering (spam filtering before or after other filtering) can be used when messages from a particular source are frequently being filtered into your junk-mail folder. By having spam filtering done after your other Email Delivery Manager filters and then creating a filter to direct email from that source into its own folder, you can save it before it reaches the spam filter.

Is the UW blocking some spam?

Yes. Email from certain sources that exclusively send large amounts of spam are blocked and discarded before they enter the UW email system. For more information, see the Blocking of Email From Some Domains page.

Is scanning for viruses also being done?

Yes, email messages are also scanned for viruses both as they come in to the UW and as they go out to the world. You can find out more on the UW Fights Viruses Web page. Email messages containing viruses may be "scrubbed" (have portions of the message contents deleted) before they are delivered to protect UW computer systems.

Does the spam scanning mean my email will be delayed?

Scanning will typically delay messages by only a second or two.

What can I do if my own messages get high spam scores?

Look at your email message to see if it has characteristics that, to PureMessage, look like spam and edit your message accordingly. You can also forward a copy of the message to help@u.washington.edu for their suggestions.

Can my own email filtering tools use the spam score?

Maybe. The score is in the header of each message that looks like spam and many email clients and anti-spam filters can read information in the header. Check the documentation or contact the vendor support for your software.

Does this mean the UW is reading my email?

The scanning is done by a program checking for the presence of specific text strings and other characteristics of messages many people consider to be spam. UW Technology staff themselves do not inspect, monitor, change, or delete email. Please see Privacy of Email and Files for more information.

What should I do if I find spam that is assigned too low a score?

Identifying spam is an inexact science. The PureMessage criteria are constantly evolving on the basis of their experience with a very large number of emails, so it represents a generalized understanding of what spam is and how to identify it. UW Technology won't be able to make adjustments to the scoring system, but will notify the vendor of needed changes. If you come upon a case that seems to be far out of line with expectations, you could forward an example (including the full email header) to help@u.washington.edu.

Adjusting the Risk Tolerance settings of your own filter is the best way to deal with low scoring spam - unless that adjustment means more good messages go to your junk-mail folder. There is no perfect setting.

Why did UW Technology choose PureMessage to do the spam scoring?

UW Technology has been testing junk email evaluation and filtering software for many months and settled on PureMessage for a number of reasons:

  • The way PureMessage works fits in well with how the UW email system works, allowing UW Technology to provide a central, high quality, high speed spam identification system without major changes in the existing infrastructure.
  • Embedding a spam score in the email messages themselves gives each person more control of how they deal with spam. They can use EDM or some other filtering software of their choice.
  • ActiveState, which makes PureMessage, has demonstrated its ability and intention to keep the spam scoring system up-to-date.
  • No changes are needed in the email client program you are already using to use the Junk Email Filtering function.
  • PureMessage has received good reviews from other higher education institutions. Stanford, for example, is using it in their campus spam management system.

UW Technology will continue to evaluate tools and methods for fighting spam. Suggestions can be sent to help@u.washington.edu