Microsoft / Outlook.com contact???

[robertg at garlic.com (Robert Glover)]

Anyone from Microsoft / Outlook.com / Office365 around?

We are having a problem with email from a certain IP being rejected with 
code FBLW15.  We have gone through the normal channels but have received 
no communication/acknowledgement from Microsoft at all. Emails to any 
domain with *outlook.com MX records are rejected with the following:

---
host
     klatencor-com0i.mail.eo.outlook.com[207.46.163.138] said: 550 5.7.1 
Service
     unavailable; Client host [65.111.<snip>.<snip>] blocked using 
FBLW15; To request
     removal from this list please forward this message to
     delist at messaging.microsoft.com (in reply to RCPT TO command)
---

We have emailed delist at messaging.microsoft.com, with no response.

The IP in question is not showing up on any blacklists that we have 
searched (mxtoolbox, multi-rbl-check, etc etc)

Thanks
-Robert