Office 365 + Shibboleth ?

[Klingenstein, Nate]

> I would be astounded to the point of speechlessness to find out that they have any client code doing ECP.

I don't know whether it's client code doing it, but we are specifically experiencing this with the Exchange(.3.9) application on iOS and Mac OS X.  The native Apple Mail client on iOS 11.0.3 worked, but we didn't check Apple Mail on OS X(10.11).