Undelivered Mail Returned to Sender - hotmail

[#1]

I'm getting the following message posting to a hotmail account via outlook. My ISP is plusnet, and my domain and its associated email is hosted at fasthosts.
The message seems to be indicating that the email cannot be received by somebody (who - fasthosts ? hotmail ?) because part of plusnet's network is blacklisted - is my reading correct and what can I do about it. The hotmail address is a valid one, as I don't have problems with email sent to it from gmail
This is the mail system at host cust-smtp-auth3.fasthosts.net.uk.
I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below.
For further assistance, please send mail to postmaster.
If you do so, please include this problem report. You can delete your own text from the attached returned message.
                  The mail system
<XXXXXXXXX@hotmail.co.uk>: host mx2.hotmail.com[65.55.92.152] said: 550
    SC-001 (SNT004-MC2F16) Unfortunately, messages from 213.171.216.60 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)

[#2]

That IP address is Fasthosts so you need to take it up with them not Plusnet https://help.fasthosts.co.uk/app/community/questions/detail/qid/84/~/emails-to-hotmail-being-rejecte...

[#3]

Yep, it's Hotmail refusing messages from Fashosts' SMTP server. Fasthosts' server is on at least 5 blacklists from what I can tell.