MSN/Hotmail has been returning a great deal of our list mail, so we
contacted them about it. It took a couple of weeks, but we finally heard
back. I am passing this information along, because it contains a contact
name/email address, as well as the list of information you need to send to
MSN to get the problem straightened out.
===================
From: "MSN Subscriber Online Support" <[log in to unmask]>

This is Kat and I understand that you are unable to send messages to MSN
Mail subscribers. We are aware of the issue that MSN subscribers are
currently having
difficulties receiving e-mail messages from non-MSN domains. To be able to
escalate your concern, we will need some specific information from your mail
provider.

Please provide us with the following information:
1) Your domain SMTP server or servers
2) List the IP address or addresses that are associated with these SMTP
servers for the domain. There may also be a range of addresses the SMTP
server operates on, in which case you will need to include the range as
opposed to the individual addresses.
3) Contact information for the domain administrator. Good contact
information should include: full name, email address and telephone
Number.
4) Exact copy of the Non-Deliverable Report (NDR) or error message received