Microcomputer Services

Filtering Junk Mail

The university filters all email to UOregon.edu in two separate ways:

Source-based Filtering
The system looks at where the message comes from and blocks all mail from known spammers and mail from sources known to be spam producers. (Source-based filtering sometimes blocks legitimate email.)

SpamAssassin
The university also uses SpamAssassin, a spam-filtering system that scans the text of an email and gives it a rating that indicates how likely it is to be spam. Email that seems to be spam can be put into a special spam folder or tagged as spam and delivered to your inbox.

Change Junk Mail Filter Settings
To change your junk mail settings, visit this web page:

https://password.uoregon.edu/spam/

You Can Opt Out of Both Filters
We recommend that you enable both source-based filtering and SpamAssassin. However, you can opt out of either spam filter or customize SpamAssassin to meet your needs. To opt out of source-based filtering, click “Disable” in the Source-Based Spam Filtering Box.

To opt out of SpamAssassin, click “Disable” in the Filtering With SpamAssassin box.

Changing SpamAssassin Options

Make sure SpamAssassin is enabled. Then use the three drop-down menus to change the options:

1. Threshold Options
SpamAssassin works by applying a set of rules that result in a score of 0 to 20 being assigned to every message. To arrive at this score, SpamAssassin looks for certain phrases, such as “You have won” and “Click here.” As the score goes up, the message is more and more likely to be spam.

If a message has a score of 0, it is very unlikely to be spam. If it has a score of 5, is probably not spam. If it has a score of 7, it is likely to be spam.

When you set a threshold of 5, that means that the UO will allow a message with a score of up to 5 to pass through to your mailbox. It will not allow a message with a score of 6 or more.

A setting of 3 will stop most spam but may catch some legitimate mail too. A setting of 20 will catch only the worst spam. It will probably not catch any legitimate mail.

The UO recommends a threshold of 5, but you can set the score as low as 3 or as high as 20 by using the drop-down menu. Remember that a threshold of 20 allows a lot of spam to get through.

2. Subject Tagging Options
You have two options:

If you want the suspected email tagged with  “*SPAM* and SpamAssassin Score,” choose this option in the drop-down menu. If you do not want the suspected email tagged, choose “Do not modify subject.”

If you are a POP user and choose to leave the subject header of spam unmodified, you will not see any visible indication that a message has been scored and flagged as spam. (See http://micro.uoregon.edu/email/popvsimap.html to learn more about the differences between POP and IMAP.)

3. Delivery Options
The delivery options control where email identified as spam by SpamAssassin is delivered. You have two options:

We recommend the option “Put spam into ‘spam’ folder.” However, if you are a POP user, choose the option  "Deliver spam to normal inbox (POP users).”

If you are a POP user and you choose to put your spam into the "spam" folder, be sure to periodically check that folder via web email to be sure that mail you want has not been incorrectly tagged as spam.

SpamAssassin Blacklist/Whitelist Preferences

In addition to the three options above, you can also put specific addresses or domains on a blacklist or a whitelist. If an email address or domain is on your whitelist, SpamAssassin will never label it as spam. If an email address or domain name is on your blacklist, it will automatically be labeled as spam. To set your preferences go to

https://password.uoregon.edu/spam/whitelist.html

Email addresses can be added to or removed from the whitelist and blacklist in the following formats. Each address that you wish to add needs to be on a separate line.

jersmith@uoregon.edu

If you want to add a blacklist or whitelist entry for an entire domain (for example, @uoregon.edu) this can be done by using a "*" as a wildcard.

*@uoregon.edu

or

*@*uoregon.edu

Note: The blacklist and whitelist preferences affect SpamAssassin only and have no effect on source-based filtering. Source-based filtering could block an address that you have put on your SpamAssassin whitelist.

Will SpamAssassin catch all junk mail?
No spam-filtering software is perfect. A message you want may be identified as spam. A message that is spam may slip through a filter. In recent tests SpamAssassin differentiated between junk mail and non-junk mail correctly in 85 percent of cases.