Outlook: Automatically Mark Items as Read

By default, Outlook doesn't mark messages as read until a client has either switched to viewing another message in the reading pane or double-clicked to open the message. To modify this setting do the following steps:

1. Click on File > Options and then click on the Mail section.
   
   
2. Click the Reading Pane button to bring up options. Check the option that reads Mark items as read when viewed in the Reading Pane.
   
   
3. You can also change the number of seconds (i.e. lower it to 1 second instead of the default 5). You'll notice that "Mark item as read when selection changes" can not be selected at the same time.
4. Once you have finalized your settings, click OK.