What I wrote is "this is Exchange on a private secure host". You snipped off the last part and hence that is quoting out of context. There is zero actual evidence (claims made in the Guardian with no actual support are not evidence) of secret NSA backdoors. This is actually one of the reasons Microsoft and other silicon valley companies have been suing the federal government - to get the ability to disclose the details of what they give the NSA and how it happens.
While some of what Snowden has claimed has been of concern other stuff is just paranoid internet urban legend - some not even from Snowden but attributed to him and others just stuff he said but has produced no proof of. And Exchange is far and away the best and most feature complete communications server package out there. Just don't use it in a public cloud setting if you're that concerned - use it with a private contractor on secure (as in all the ports are encrypted) servers and you're fine. Remember, what I am referring to here is a different type of email than most people use. I need it for work and use it personally too but it is not typical.
While some of what Snowden has claimed has been of concern other stuff is just paranoid internet urban legend - some not even from Snowden but attributed to him and others just stuff he said but has produced no proof of. And Exchange is far and away the best and most feature complete communications server package out there. Just don't use it in a public cloud setting if you're that concerned - use it with a private contractor on secure (as in all the ports are encrypted) servers and you're fine. Remember, what I am referring to here is a different type of email than most people use. I need it for work and use it personally too but it is not typical.