Stopped by the suppression list important
The message was not sent because its recipient or domain is on the suppression list.
In detail
A failure we caused on purpose, carrying the code and description configured on the suppression row. It is a success of the mechanism, not a delivery problem — and counting it as a bounce would make a well-maintained list look like a failing one. Worth surfacing separately in analytics for the opposite reason too: a rising count here means the audience is being sent to addresses we already know are dead, which is a problem upstream in the list, not in sending.