After many hours of searching the web and trying work arounds I seem to have fixed my exchange bug in Mail.
My problem was:
No mail in exchange account after installing Mavericks. Mailbox simply didnt build and no new mail was received. The Mavericks update didnt work out for me, so I was becoming more than frustrated.
Solution:
I noticed Mail used another exchange server in accounts then I use on my iOS devices. Seems like the "auto detect" option in accounts chose another server. After overriding auto-detect I manually entered the server used on my iOS devices et voila, it works.
Small issue
Only one small issue left..it looks like new mails are being pushed to Mail with a slight delay. I can live with that for now.