So this was a new one for me… I use the Reading Pane in Outlook quite a bit, but I didn’t realize you could control how long it takes for an email to be marked as Read based on how long it appears in the Reading Pane. Here’s how you do it…
Go into Outlook and select File > Options > Mail > Outlook panes, and select the Reading Pane button:
In the Reading Pane dialog box, you can select to have items marked as read when they are viewed in the Reading Pane, and you have the option to select how many seconds it’ll take before that happens!
One Minute Office Magic 