Recently I worked with a customer that who was experiencing some odd spam false positive behavior. Even though they had purchased and deployed a third-party spam filter, Exchange was still evaluating each piece of mail and moving suspected spam emails into each user's Junk Mail folder. This was considered undesired behavior. Any mail that made it past the third-party spam filtering appliance was to be treated as known-good.

Unfortunately you can't simply disable the native Exchange spam filter, but you can achieve equivalent behavior. Here's how:

Examine the email headers (in Outlook 2010, File -&gt; Properties -&gt; Internet Headers) and note the value of the <strong>X-MS-Exchange-Organization-SCL</strong> line. In this case, the value was 9 (out of a possible 9) meaning Exchange had analyzed the email and determined (with a high degree of confidence) that it was spam.

<a href="http://egroup.jasonmangone.com/wp-content/uploads/2012/01/JunkedEmail.png"><img class="alignnone size-medium wp-image-5831" src="http://egroup.jasonmangone.com/wp-content/uploads/2012/01/JunkedEmail-300x229.png" alt="" width="300" height="229" /></a>

Launch the Exchange Management Shell (it's Powershell for Exchange). It should connect to your Exchange server automatically. Run <strong>Get-OrganizationConfig</strong> and note the value of the <strong>SCLJunkThreshold</strong> line. This value determines the maximum spam rating that is allowed to go straight to a user's mailbox. Mail with a higher rating will go to the Junk Mail folder instead. This field accepts a maximum value of 9, so if we set it to 9 we will effectively tell Exchange to trust all incoming mail.

<a href="http://egroup.jasonmangone.com/wp-content/uploads/2012/01/SCLThresh81.png"><img class="alignnone size-medium wp-image-5832" src="http://egroup.jasonmangone.com/wp-content/uploads/2012/01/SCLThresh81-300x160.png" alt="" width="300" height="160" /></a>

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Run <strong>Set-OrganizationConfig -scljunkthreshold 9</strong>.

<a href="http://egroup.jasonmangone.com/wp-content/uploads/2012/01/SetSCL9.png"><img class="alignnone size-medium wp-image-5834" src="http://egroup.jasonmangone.com/wp-content/uploads/2012/01/SetSCL9-300x97.png" alt="" width="300" height="97" /></a>

You can view the new value has taken effect by re-running <strong>Get-OrganizationConfig.</strong>

<a href="http://egroup.jasonmangone.com/wp-content/uploads/2012/01/SCLThresh9.png"><img class="alignnone size-medium wp-image-5833" src="http://egroup.jasonmangone.com/wp-content/uploads/2012/01/SCLThresh9-300x180.png" alt="" width="300" height="180" /></a>

There's no need to run this command on each Exchange server - just run it once on any server and it replicates to other mail servers in the organization.

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