Need technical advice asap

Today I sent a really benign email to one of my friends with a "hotmail.com" address.  My message got rejected twice in a row, and I have no idea why.

Here's the text of why it got rejected.  I can't make heads or tails of it.

Any feedback/advice?

Reporting-MTA: dns; fed1rmmtao106.cox.net
Arrival-Date: Sun, 30 Sep 2007 16:44:53 -0400
Received-From-MTA: dns; fed1rmimpo01.cox.net (70.169.32.71)

Final-Recipient: RFC822; <m************> actual email address hidden by me.  I do NOT send junkmail to any Hotmail account.  I rarely even send anything to hotmail account users.  WTF?

Action: failed
Status: 5.1.1
Remote-MTA: dns; mx1.hotmail.com (65.54.244.136)
Diagnostic-Code: smtp; 550 Mail rejected by Windows Live Hotmail for policy reasons. A block has been placed against your IP address because we have received complaints concerning mail coming from that IP address. We recommend enrolling in our Junk E-Mail Reporting Program (JMRP), a free program intended to help senders remove unwanted recipients from their e-mail lists. For enrollment instructions, please refer to: http://postmaster.live.com/... For additional information about Microsoft's technical guidelines, please refer to: http://postmaster.live.com/...

Gabriele