Earlier this morning Hotmail and their partner domains (i.e. MSN.com, Live.com and Sympatico.ca) began to experience connectivity issues which appear to have affected every major ISPs and Email Service Provider around the World. The Hotmail network began to return 4.x.x errors and were rejecting connections from external mail senders. At approximately 12:15 PM (EST) these issues began to be resolved and the Windows Live team updated their systems notices.
To get news like this as it happens make sure your following @emailkarma on Twitter.
To track issues with Hotmail point your browser over to http://www.windowslivehelp.com/, where you will find alerts of any issues that the Microsoft Live product suite is currently experiencing.