What data file types does Outlook support? While working with Outlook, you will encounter two data file types: OST and PST. OST (Offline Storage Table) file types allow you to work offline.

Once you have located the OST file, follow the methods below to open the it. Method 1: Using Free Xst Reader Tool Xst Reader is a free open-source viewer that allows you to open and view OST and PST ...

There are several reasons why you can’t open Outlook, such as corrupt or damaged files, problematic add-ins, or your computer has a virus that is causing Outlook to be unresponsive.