All email sent to various hotmail addresses rejected?

[#1]

I've started to get this error and email messages returned to me this week when I try to send emails to Hotmail addresses

Quote

550 OU-002     (SNT0-MC4-F54) Unfortunately, messages from 46.32.252.12 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. (in reply to MAIL     FROM command)

Is this a PlusNet problem?
Many thanks in advance for any help.

[#2]

It looks like your IP is blacklisted for some reason :
http://mxtoolbox.com/SuperTool.aspx?action=blacklist%3a46.32.252.12&run=toolpage
Are you on a static IP ? If you aren't then try disconnecting your router for a few minutes and reconnecting and see if you get assigned a different IP address

[#3]

Actually - that IP address doesn't appear to be a Plusnet one - it seems to belong to vps-10.com

Quote

% Information related to '46.32.252.0 - 46.32.253.255' % Abuse contact for '46.32.252.0 - 46.32.253.255' is 'abuse@heartinternet.co.uk' inetnum:        46.32.252.0 - 46.32.253.255 org:            ORG-HI14-RIPE netname:        HEART-INTERNET descr:          Heart Internet Ltd country:        GB admin-c:        HC1559-RIPE tech-c:        HC1559-RIPE status:        ASSIGNED PA remarks:        INFRA-AW mnt-by:        MNT-WEBFUSION source:        RIPE # Filtere

[#4]

Ah, right - now I know where to go. Not a PlusNet problem.
I'm on a static IP here at home but at work we are dynamic - further reinforcing your thoughts.
Thanks Dom, much appreciated.