Outlook for Mac is a locally cached email client
Original KB number: 2800895
We do not recommend that you change the default location of your Profile folder for Microsoft Outlook 2016 for Mac, or your Identity folder for Microsoft Outlook for Mac 2011 to an external hard disk or to a network. Additionally, using a mail identity or profile that is located on an external hard disk or on a network is not supported in either version of Outlook for Mac.
Outlook 2016 for Mac caches your mail items in a profile in your home folder at the following location:
~/Library/Group Containers/UBF8T346G9.Office/Outlook/Outlook 15 Profiles
Outlook for Mac 2011 caches your mail items in an identity in your home folder at the following location:
~/Documents/Microsoft User Data/Office 2011 Identities
Like Microsoft Entourage for Mac 2008, Outlook 2016 for Mac and Outlook for Mac 2011 are intended to be purely locally cached mail clients. Changing the location or using a mail identity that is located on an external hard disk or a network is not supported.