Spam confidence level (SCL)

Microsoft assigns a spam confidence level (SCL) to inbound messages that go through spam filtering and are assigned a spam score. That score is mapped to an individual spam confidence level (SCL) that's added to the email. A higher SCL indicates a message is more likely to be spam.

SCL Value Description
-1 The message skipped spam filtering. For example, the message is from a safe sender, was sent to a safe recipient, or is from an email source server on the IP Allow List.
0, 1 Spam filtering determined the message wasn't spam.
5, 6 Spam filtering marked the message as spam.
8, 9 Spam filtering marked the message as high confidence spam.

For more information, see Spam confidence level (SCL).