Microsoft domains not accepting from our Static IP. outlook.*, live.*, hotmail.* etc.

[flattened]

Hi,

This problem is only occuring with Microsoft hosted email domains - everyone else is fine. It does not like our Static BT IP. We are not on ANY spam or whatever blacklists.  The entire error (with IP & address snips!) is at the bottom. But here is the telling bit (for me!)

"BAY0-MC1-F9.Bay0.hotmail.com #550 SC-002 (BAY0-MC1-F9) Unfortunately, messages from 81.x.x.x weren't sent. Please contact your Internet service provider since part of their network is on our block list. You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. ##"

Who do I speak to about our IP?

An error occurred while trying to deliver this message to the recipient's e-mail address. Microsoft Exchange will not try to redeliver this message for you. Please try resending this message, or provide the following diagnostic text to your system administrator.

The following organization rejected your message: BAY0-MC1-F9.Bay0.hotmail.com.
Diagnostic information for administrators:

Generating server: xxxxxxx.xxxxx.local

BAY0-MC1-F9.Bay0.hotmail.com #550 SC-002 (BAY0-MC1-F9) Unfortunately, messages from 81.x.x.x weren't sent. Please contact your Internet service provider since part of their network is on our block list. You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. ##

[markp]

Hi flattened,

I am sorry to see you are getting errors when sending mail, from the error message it looks like hotmails server is blocking your email.

Have you contacted the helpdesk?

If not I would advise you to do so, they will need to know what email address you are sending from and too, plus the full error message and IP.

Regards

Markp