When browsing through your Outlook emails, it’s easy to accidently open the wrong emails resulting them in being marked as read. By default Outlook will mark any email you open as read, even if its only open for a fraction of a second. Now, unless you’re the almighty master of speed reading, chances are you won’t be able to read through them faster than you can click them so I have a fix for ya.
Outlook has a setting in the options menu that will allow you to add a delay to how long it takes to mark your messages as read. Once you have it set, Outlook will wait for the allotted amount of time before automatically marking the email as read. Read on to learn how to set this up.
How To Add A Delay To Messages Being Marked As Read In Outlook 2010
1. In Microsoft Outlook 2010 Click the File tab, and then from the menu Click Options.
Note: – For Outlook 2007 – Tools, Options, Other, Reading Pane to adjust Mark as read settings

2. In the Options window, Click Mail, then scroll down to Outlook Panes and Click Reading Pane…

3. Check the box for Mark items as read when viewed in the Reading Pane, then Enter the Number of Seconds you would like Outlook 2010 to wait before marking your email as read. Keep in mind this number will be applied to all emails opened from now on regardless of their size, so aim for the average time it takes you to read your emails.
Now whenever you read an email, Outlook will wait for you to have that email open for X seconds before marking it as read.
If there are emails that you have sitting around that you want to quickly Mark as Read you can Right-Click any email and then Select Mark as Read. This works to Mark mail Unread too. To mark multiple messages use Shift+Click or Ctrl+Click to select all of the ones you want to do in one batch.

