For the most efficient spam filtering in Outlook, follow the ISU's PerlMX Filters procedure below.

ISU's PerlMX Filters

Iowa State's PerlMX spam tagging system examines all messages coming to campus and calculates the probability that the message is spam. PerlMX creates special headers that Outlook uses to filter e-mail into spam or non-spam categories. The filters or rules Outlook uses to filter spam from PerlMX headers are located in the Rules and Alerts dialog. Follow these steps to create rules based on the PerlMX headers.

1. Outlook 2010, Click the File tab, then Manage Rules and Alerts. Outlook 2007, click Tools > Rules and Alerts.
2. Click "New Rule".
3. Under Start from a blank rule, select "Apply rule on messages I receive," (2010) or "Check message when they arrive," (2007) and click "Next ".
4. To adjust how Outlook handles the headers created by PerlMX, check "with specific words in the message header," and click the "specific words" text in the Step 2 box.
5. Under "Specify a word or phrase to search for in the message header," enter Gauge=XXXXX to filter based on a PerlMX probability of 50 percent or more (each X represents ten percent; add or subtract Xs as needed). Click "Add", then "OK", and finally "Next".
6. Check "move it to the specified folder" and click the "specified" text in the Step 2 box.
7. Under "Choose a folder" select Junk E-mail, then "OK," then "Next".
8. Check the boxes next to any exception to this rule and click "Next".
9. Give the new rule a name and check the box next to "Turn on this rule". Check the box next to "Run this rule now to messages already in the Inbox" to filter message you have received with this new rule.

Junk E-Mail Options

Outlook also has a built-in Junk E-mail filter with four levels of spam filtering: Safe Lists Only, High, Low, and No Automatic Filtering. The default setting is Low.

IT Services recommends leaving this filter set at the default level to lessen the chances of non-junk e-mail being filtered to the Junk E-mail folder. If you do adjust these settings, it is a good idea to review the contents of your Junk E-mail folder before emptying it.

For information on adjusting Outlook's Junk E-mail filter, see the help file in the program or visit this Microsoft site: http://office.microsoft.com/en-us/outlook-help/change-the-level-of-protection-in-the-junk-e-mail-filter-HP010356454.aspx