I too am with orange and I too use Outlook. When Orange took over from Wannado I had difficulty in messaging Outlook, both sending and receiving mail. I went back to Outlook express, set it up as my email agent, then selected Outlook and made it the default. It worked!
at the time of outlook failure I phoned Orange, and was told that Orange did not support Outlook, for what that is worth.
I am using it all the time now.