Ny way to see why Outlook’s client junk mail filter is marking a message as spam

outlookspamspam-filter

I have some users running Outlook 2007 connected to an Exchange server, and they're complaining about mail ending up in their junk box. There's no X-SCL tag in the mail headers so this filtering must be happening in Outlook itself, rather than Exchange. It would be helpful to see how Outlook is determining whether the email is spam, so I was wondering – is there any way to turn on additional logging or diagnostics in Outlook to see why it's marking the email as junk? Of course they could always use the safe senders list but it would be nice to get some more information about it, something like Exchange's X-SCL header, or SpamAssassin's X-Spam-Status.

Best Answer

Unfortunately, Microsoft guards their Junk Email filter like Fort Knox.
Here is a link to a pdf that describes some interesting information about how the Junk Email filter works, but as the author admits, it's by no means documentation of the product. It's just his discoveries.
As a developer, there isn't even a documented API for the Junk Email filter so that you can tell it to examine email headers... Microsoft definitely keeps this information close to the breast.

Related Solutions

Enforce mail rules server-side in Exchange 2007

Exchange 2007 offers Message Transport rules to filter messages based on a number of conditions. One of these conditions is the HeaderContains condition which should do what you want.

To get it to send the mail to your Junk folder, you could set-up SCL to send messages over a certain threshold to the junk folder, then get the message transport rule to stamp an SCL value on the message, higher than that threshold, should that header exist.

Details of what filtering Message Transport Rules support is available here.

Details of how to enable Message Transport Rules can be found here.

Exchange 2007: Move messages with SenderID fail to Junk Mail Folder

According to Technet:

Outlook neither displays the Sender ID status nor necessarily flags a message as junk at certain Sender ID values. Outlook uses the Sender ID status value only during the calculation of the SCL value.

If you are using Exchange 2007 you could setup a transport rule that adjusts the SCL level based on the Sender ID status, so that it is picked up by the junk filter. Alternatively you could adjust your SCL level so that emails with invalid Sender ID are picked up as spam, but that may lead to more false positives.

To setup a transport rule you need to look in the header, the SenderID filter adds the following to the email header:

X-MS-Exchange-Organization-SenderIdResult:<status>

So you need to create a transport rule to do the following:

Conditions: When a message header contains specific words (failed status's)
Actions: set the spam confidence level to value
Exceptions: except when the text specific words appears in a message header.
(valid status's)

Best Answer

Related Solutions

Enforce mail rules server-side in Exchange 2007

Exchange 2007: Move messages with SenderID fail to Junk Mail Folder

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