smnirosh..
you changed things without knowing all your infrastructure and without asking BEFORE.
I guess that outlook clients are trying to connect externally, but since you've setup your main internal domain like your external one, all *.yourdomain.tld hosts are resolved internally.
I suggest you to revert to the old domain name, fix client auth, then sit down in front of a piece of paper, design a diagram of all you have there, note how it works now and how it is supposed to work, think about how you wish things work, then ask here for support.