To setup your Walla Walla University email in Mac Mail perform the following steps. The steps for Outlook for Mac are very similar.
Launch the Mac Mail application and from the Mail dropdown select Accounts… from the list.
Check to see if you have any existing WWU Exchange connections setup. If so, delete them.
Click the + icon to add a new account.
When prompted, select the Exchange account option and Continue.
Type in your email address and password then click Sign In.
Select what items you wish to sync and click Done.