Outbrain emits ob_click_id (your unique click), ob_source (publisher), ob_section (placement), and ob_position. Forward ob_click_id to your tracker as the postback key. ob_source and ob_section are the two highest-signal sub-IDs for blacklisting.

?ob_click_id={ob_click_id}&ob_source={ob_source}&ob_section={ob_section}&ob_position={ob_position}