This data file is associated with a mail account. To remove it use the ‘Email’ tab. An OST file is an offline folder file in Microsoft Outlook.

If you get Your Outlook data file cannot be configured error when opening Microsoft Outlook and your email account, see this post for the fixes.

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.

Free add-ons for Outlook and Thunderbird let you save all or selected e-mail attachments to a folder on your PC, and Yahoo Mail lets you download attachments in bulk—something you can't do ...