Note: This should be only performed if advised by your administrator, as disabling AutoDiscovery on the client will cause that configuration changes will not be automatically discovered!
1.) Start Outlook on the affected MAC client
2.) open Applications > Utilities on your computer and the double-click the AppleScript Editor.
3.) Copy/Paste these three lines into a new AppleScript Editor window.
tell application "Microsoft Outlook"
set background autodiscover of exchange account 1 to false
4.) Click the Run button in the AppleScript Editor window. If you receive no error messages then everything worked.
To learn how you can disable various AutoDiscovery options for MS Office on a Windows PC click here.