400+ GB system data

sevencrows wrote:

By scrolling thru the various libraries & containers in with Finder, I've identified 169 GB of the 400 GB (320 GB, 370 GB 425 GB keeps changing) in Library>UBF8T346G9.Office and about 165GB is the subfolder UBF8T346G9.Office>Outlook. I'm afraid to delete the contents of these subfolders because I don't know what I'm deleting. My Outlook app shows about 7 GB stored on disk and lists all the "outlook" folders and sizes where emails are stored. If I have only 7 GB or so of emails & attachments, what's the other 160 something GB's? Is it safe to delete it?

Thanks,

If you delete anything in that Office directory, it is likely that Outlook and the calendar will stop working. Outlook will lose its index and not be able to find emails and calendar items.

Some of that storage could be associated with the Calendar, or possibly with the Sent and Deleted email folders. Have you emptied the trash (Deleted folder) in Outlook? Do you ever pare down your Sent folder? Sometimes these folders can grow huge over time. Depending on how Office is implemented on your server, there can be a large Online Archive which, if mirrored on the computer, can be huge.

How are you measuring the size of your Outlook folders? Are you using the Properties option?

... also I am guessing that the mystery storage is taken up with either Outlook files/folders stored "locally" on your Mac versus online on the Exchange Server, or is taken up with email attachments.

In any case, deleting files or folders in that Outlook folder inside your Library will result in Outlook no longer displaying or locating emails properly. If all else fails to bring relief, I can only suggest making good backups of everything and then completely uninstalling Outlook and signing out of your account, then reinstalling and signing back in.

https://support.microsoft.com/en-us/office/clear-the-cache-in-outlook-for-mac-6f230dfa-7f12-4606-bb1a-55ee19087033

The above cache clearing might help.

Also, in your audit of storage being taken up, are you including the local Outlook mail folders that are not on the Microsoft Exchange server.

Finally, you can see your email usage separately with Web Outlook:

1. Log in to Outlook Web at https://outlook.office.com.
2. Click the gear icon (Settings) in the top right corner.
3. Type "storage" in the search box, then select "Storage" or go to "Account" > "Storage".
4. Check the amount of storage used and the total mailbox size.

If none of this is fruitful, it might make sense to back up all your Outlook emails and then remove and reinstall Outlook.

(Caveat: I used to use Outlook for work emails but no longer do so I am going from memory on the above ...)

sevencrows wrote:

By scrolling thru the various libraries & containers in with Finder, I've identified 169 GB of the 400 GB (320 GB, 370 GB 425 GB keeps changing) in Library>UBF8T346G9.Office and about 165GB is the subfolder UBF8T346G9.Office>Outlook.

That is one of the places where Outlook stores email and calendar attachments, notably files that can be displayed inline like image files and pdfs.

A Good Article On What Ststem Data Is

What is System Data in Storage Settings?