There you go:
Date: Fri, 23 Apr 2010 09:10:45 +0200
MIME-Version: 1.0
Content-Type: multipart/alternative;
boundary="----=_NextPart_000_001C_01CAE2C4.DB412EF0"
X-Priority: 3
X-MSMail-Priority: Normal
X-Mailer: Microsoft Outlook Express 6.00.2900.5843
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579
X-Antivirus: avast! (VPS 100422-1, 22/04/2010), Outbound message
X-Antivirus-Status: Clean
Here is the bounce header (from Hotmail)
Subject: Delivery Failure
X-SmarterMail-Spam: Bayesian Filtering, DK_None, DKIM_None
X-SmarterMail-TotalSpamWeight: 10
X-Antivirus: avast! (VPS 100422-1, 22/04/2010), Inbound message
X-Antivirus-Status: Clean
1)-3) correct. Now add 4) All domains now sending to hotmail with no issues.
Both hosting company and ISP are aware of problems with Hotmail which seem to stem from the switch to Windows Live Hotmail.