I know this, but this doesn't have anything to do with Autodiscover... this is. just installing a certificate on your Apple device. And also Apple show this as a unsigned certificate.
I don't think a customer wil be very willing to add a key to their Windows registry. A lot of them don't even know what a registry key is.
So disappointing that there isn't a real solution to this problem! This has been abound for so long and still no solution.
Also the lack of support for IOS /...
I have been following this topic for a while. I'm having the same issues and wondering how much more time it will take to fix this. I believe you are working hard to fix it... but it has been months already (about 10). This is a very annoying problem.