Outlook does not use a PST. All mail is stored in ~/Documents/Microsoft User Data
Please post further questino regarding Outlook on Microsoft's own forums for their Mac software as Apple Communities only provide support for Apple products:
I just called Microsoft as I wanted to back up my "pst" file on my MBA. Turns out that there is no pst file in outlook for mac 2011. Instead it relies on a database that is located as below:
- Microsoft User Data
- Office 2011 Identies
- Main Identity
The "main identity" folder holds all the data from email, calander, etc.
Its usually a good idea to back up this folder from time to time in the event outlook crashes or gets corrupted you always have a backup folder.
I just downloaded about 8 gigs of emails from my gmail account. In the older versions of outlook the pst file used to get unstable at about 1.5 gigs. Not sure when it gets unstable in the latest version, but I've been bitten twice with lost data so I'm not risking it again and backing up.
Good luck with your data.