Sending, receiving, and organizing email in Outlook.com
I think you are looking for the MSRC reporting portal at https://msrc.microsoft.com/report/abuse .
Probably Submit Abuse Report (CERT) at https://msrc.microsoft.com/report/abuse?ThreatType=IpAddress&IncidentType=IllegalViolatesTheRightsOfOthers
But you said you've already done a CERT? Not sure what else you might be looking for.