Configuring preferences and options in Outlook.com
Hi Steve Upchurch,
Thank you for posting in Microsoft Q&A.
If you are using Outlook.com in a web browser, please try moving your mouse pointer over the sender's profile picture/avatar area on the left side of a message. In some Outlook views, the message selection checkbox only appears when you hover over that area.
If the checkbox still does not appear, could you please provide a screenshot (with any personal information hidden) and let us know whether the issue affects all folders or only a specific folder?
Kind regards.