Yesterday I was sending to hotmails ok. Today I'm not

I get
Reason: Remote host said: 550 SC-001 Mail rejected by Windows Live Hotmail for policy reasons. Reasons for rejection may be related to content with spam-like characteristics or IP/domain reputation problems. If you are not an email/network admin please contact your E-mail/Internet Service Provider for help. Email/network admins, please visit MSN Postmaster for email delivery information and support
I have followed the suggested sender ID path and changed the DNS Text record to the generated one and still back comes the message. There is NO spam in the email!
What are they up to?