exchange under mountain Lion
Using exchange in mountain lion mail will not populate
MacBook Air, OS X Mountain Lion (10.8.2)
Do not try to set up an Exchange account from within Mail. Use System Preferences > Mail, Contacts & Calendars.
Select Exchange and provide your company's user name and password. You will also need your Exchange Server Address which will resemble mail.companyname.com. Ask your company's IT department for it. If they tell you they don't support Apple just tell them that you are trying to configure your iPhone or iPad for company email - the information is the same.
That is all that should be required.