Hi kultarr,
The search feature for Outlook for Mac is a client feature.
Since our forum focuses on Office 365 Online services and we can just provide limited assistance on such client features, I suggest you post this question with the detailed information in the Outlook for Mac forum below for more professional suggestions:
http://answers.microsoft.com/en-us/mac/forum/macofficeo365-macoutlook?sort=lastreplydate&dir=desc&tab=Threads&status=&mod=&modAge=&advFil=&postedAfter=&postedBefore=&threadType=All&tm=1415081873813
Your time and understanding is highly appreciated.
Best regards,
Kid Yang