The X-pstn-settings header will not available in a message that was delivered to multiple (envelope) recipients. However, if the sending mail server establishes a separate connection for each recipient, then an individual recipient’s spam settings information will be displayed in the header.
The parenthesized pair of numbers indicates the user's base threshold and
effective threshold. These are derived values and should not be directly interpreted, as they are subject to change.
If any C, M, P, or R filter that the user turned on has a value less than 85, the
effective threshold value is a multiple of the base threshold value. If none of these filters is less than 85, the threshold value is the same as the base value.
The final letters on the line indicate what filters the user had turned on and which
had values less than 85 (these are in upper case). In the above example, the make-money-fast (M) and the commercial offer (C) category filters were triggered.