The short answer
Yes. Rebuilt or re-downloaded automatically when needed.
What is it?
Temporary data of Microsoft Outlook inside its sandbox container, such as web content and downloaded resources. Your mail database is stored separately, in the Office group container.
What happens if you delete it?
Outlook rebuilds it as needed. Mail, calendars and contacts are not stored here.
How to remove it properly
Quit Outlook, then move ~/Library/Containers/com.microsoft.Outlook/Data/Library/Caches to the Trash.
Quit the app that uses it, then move it to the Trash. Empty the Trash when you’re sure.
How MoreRoom helps
MoreRoom recognises this item, shows its real size and when it was last used, and labels it “Safe to remove”. In the free version you can move it to the Trash in one click, with Undo; Pro collects every safe item at once.
Frequently asked questions
Is it safe to delete the Microsoft Outlook cache on Mac?
Yes. Rebuilt or re-downloaded automatically when needed. Outlook rebuilds it as needed. Mail, calendars and contacts are not stored here.
Will Microsoft Outlook cache come back after I delete it?
Yes. Outlook rebuilds it as needed. Mail, calendars and contacts are not stored here.
How do I remove Microsoft Outlook cache properly?
Quit Outlook, then move ~/Library/Containers/com.microsoft.Outlook/Data/Library/Caches to the Trash.