Reporting-MTA: dns;blu0-omc3-s19.blu0.hotmail.com
Received-From-MTA: dns;BLU174-DS21
Arrival-Date: Sun, 25 Aug 2013 16:47:50 -0700

Final-Recipient: rfc822;*** Email address is removed for privacy ***
Action: failed
Status: 5.5.0
Diagnostic-Code: smtp;554 The mail could not be delivered to the recipient because the domain is not reachable. Please check the domain and try again (1479978268:301:-2147467259)

I've been struggling with this error for the past few days. It seems to have happened after the recent Outlook.com outage.

DOMAIN above is iptech1

When trying to compose an email through outlook.com directly, you get this message: "The address may not be valid" for any email in that domain.