I am sure that Office 365 works brilliantly, but I prefer solutions where I have control over the product and I can upgrade when I want to not when Google or Microsoft decide to upgrade me. Also not to sound paranoid, but especially since the NSA Mass surveillance, I am not keen on cloud based products especially email.

I am sure Office 365 works brilliantly, but I prefer in house solutions. I like what I see with this Mdaemon Messaging Server.