Yes Chris there is an issue with hotmail.com and outlook.com both microsoft email services.
Messages from hotmail.com and outlook.com inbound to TalkTalk are being bounced with a TT992 rejection. That's the TalkTalk spam protection process in action. What I have discovered is that SORBS SPAM is listing at least one (but probably more) of the sending IP addresses that hotmail and outlook.com use to send mail messages to TalkTalk. TalkTalk employs CloudMark to protect its network and customers from spam and CloudMark in turn gathers sender intelligence from TalkTalk users marking as spam any suspect messages, as well as spam detection by agencies like SORBS SPAM.
Bottom line is that SORBS SPAM will automatically remove IP addresses from spam listings when no more spam is detected by spam traps. And will accept requests for de-listing by Microsoft email admins when those admins are able to confirm they've done all they can to stop spam sending at source. i.e When Microsoft have identified the spamming accounts and removed access for the spammers. This process is called improving the sender reputation. So basically when Microsoft improve the sender reputation we'll be back to normal and there'll be no reason to block any mail from hotmail.com or outlook.com email addresses.
The issue has been reported to TalkTalk and I'd be sure that the Microsoft email admins have picked up on the TT992 email rejections.
We may hear more tomorrow.
