Outlook, assuming that everyone knows how to read its special formatting, puts it all into a tidy little package that Apple’s Mail app (and many other email applications) can’t read.

You can find your Outlook data files by navigating to the Data Files tab via File > Open & Export > Open Outlook Data File. If you use Outlook New, you won't have a File tab.

Alternately, you can locate the Outlook OST file using Windows Explorer. Open Windows Explorer, click the "C" drive icon, and double-click the "Users" folder to open it.

Outlook users can now open Office documents that they receive as attachments in their respective apps. If you don’t have them installed, Outlook will prompt you to download them from the App Store.