Do you have an outlook.office365 subscription?
I would try to re-add that account again to see how it goes.
Here is a link that might help you on how to set up an exchange mail server: http://office.microsoft.com/en-us/office365-suite-help/configurer-la-messagerie-sur-windows-phone-HA102823194.aspx?CTT=5&origin=HA103787376
I have the same problem with my Office365 subscription -- neither one works on my new Lumia 925 which I otherwise love. Since it is now 6 September and the same issue has been happening for me since I updated to 8.1 more than two weeks ago it does look
like this is an update glitch.
Any news on IT people having success? No point involving our IT here in Darwin if Adelaide is getting nowhere. I agree one of the main points of going Windows phone was to access work email -- without buying an iPhone! -- so this is pretty frustrating.
Any MS staff checking these feeds? Any ideas or at least temporary work-rounds? I can't even get the excellent Remote RDP app from the Windows store so this is totally stymie stuff.
Getting impatient, alas...