My Hotmail (both on Outlook.com and my iPhone) received no new emails between about 4am and 11am UK time this morning. It has let me send them in that time. Since 11am I have received emails, but none of the ones sent to me between 4 and 11 have arrived. I know emails were sent in that time and I was expecting an extremely important email in that time also, so am keen to recover them. 

What is going on?

Harry