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How to display IMF's Spam Confidence Level (SCL) rankings in Microsoft Outlook

Learn how to create a custom Microsoft Outlook form that exposes Exchange Server Intelligent Message Filter's Spam Confidence Level (SCL) rankings for all incoming e-mail.


When the Intelligent Message Filter (IMF) is running on Exchange Server, all messages processed by it are labeled...

with a value called the "Spam Confidence Level" (SCL).

The SCL is a ranking that IMF gives an e-mail on a range of 0 to 9. Most of the time, messages ranked 8 or above are definitely spam. But it is possible to have a legitimate message stamped with a high spam score, because it has certain spam-like attributes.

I've noticed, for instance, that legitimate (if non-whitelisted) messages with many hyperlinks in them tend to be scored as spam regardless of where the links lead.

The SCL isn't normally shown on messages received in Microsoft Outlook, but it can be useful to have it displayed. This isn't something you can do with Microsoft Outlook's out-of-the-box options though.

For now, the only way to do it (for now) is to create a custom Microsoft Outlook form that exposes the SCL Property.

The folks at Microsoft's You Had Me At EHLO blog have an example of how to do this, which I'll recap here:

  1. Open Notepad and copy and paste this script (from the above-mentioned article) and save it as SCL.CFG.
    ;**********The CFG file**********
    DisplayName=SCL Extension Form
    Comment=This forms allows the SCL to be viewed as a column
    Owner=Microsoft Corporation
    Contact=Your Name
    ;**********END CFG

  2. Copy that file to the directory that has your Outlook Forms repository. Typically this is C: \Program Files\Microsoft Office\OFFICE11\FORMS\<language ID>, where <language ID> is the language-locale number for your installation of Office. For U.S. English, that's 1033; the number will vary depending on what version of Office you have installed.

  3. Open Microsoft Outlook and go to Tools -> Options -> Other -> Advanced Options -> Custom Forms -> Manage Forms.

  4. Click Install and select SCL.CFG to add it to the forms library. Click OK to close out all dialogs.

  5. Go to the mailbox where you want to expose the SCL value, right-click on the column headers and select the Field Chooser.

  6. At the top of the Field Chooser, click the dropdown and select Forms….

  7. Add the SCL Extension Form, which will then appear in the dropdown menu.

  8. When selected, it will give you the choice of adding an "SCL" column. Add the column as needed.

Note that the SCL column will not populate if you're using Microsoft Outlook in conjunction with just the local Junk E-mail filter. It only shows values with e-mails received from Exchange Server and processed with the Intelligent Message Filter.

About the author: Serdar Yegulalp is editor of the Windows Power Users Newsletter.


Am I correct in assuming that what this does is read the [SCL] mail header and display it in the messages grid?

I have been attempting to modify this script to display other headers (that are not already available in Microsoft Outlook), but I only get a blank column in my messages grid in Microsoft Outlook. I have Googled this topic with no success. It seems like there is a big back hole in the area of "exposing headers in Microsoft Outlook," and in "outlook.cfg" files.

Any help would be greatly appreciated.
—Daniel O.


I believe what's actually happening here is the form is exposing a property on the message that has been provided by the Exchange server in the X-Exch50 blob -- a set of metadata properties that move with the message but are separate from it. The x-header added to the POP3 version of the message headers is not what's actually read; it's just added to the message as a way to include that property with it if it ever gets moved out of Exchange.

From what I can tell, exposing arbitrary headers as columns doesn't seem possible yet, but if I do find a way to do it I'll post it as a tip.
—Serdar Yegulalp, tip author


This is a great tip that worked wonderful in Microsoft Outlook 2003, but now I have Microsoft Outlook 2007 and it doesn't work. Do you know if there is a fix?
—Phil B.


I got this working in Microsoft Outlook 2007 as well, so I'm not sure what might be wrong. I was able to follow the same series of steps to expose the SCL.

If you're having trouble finding the SCL.CFG file, remember that you need to go to the directory where you installed it; the Forms manager doesn't open to that directory automatically.

Also, when you're in the Field Chooser and you go to the "Select Enterprise forms for this folder" view, you need to remove everything from the "Selected Forms" column FIRST before adding the "SCL Extension Form." Otherwise the SCL Extension Form won't appear.

—Serdar Yegulalp, tip author

Do you have comments on this tip? Let us know.

Related information from

  • Tip: Simplified Exchange IMF Spam Confidence Level rankings for Outlook
  • Tip: How to enable the Exchange IMF on authenticated SMTP connections
  • Tip: Configuring Microsoft Outlook to display Sender ID information
  • Learning Guide: How to fight spam on Exchange Server
  • The spamfighter's toolbox

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  • This was last published in March 2006

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