By default, Outlook is configured to mark a message read a few seconds after the message is selected. This can result in messages accidentally marked as read.
You have the choice of automatically marking messages read after a few seconds, marking messages read when you select another message or never marking the messages read (by having both options unticked.)

My preference is to never automatically mark messages read. They will be marked as read if I double click to open or Reply/Forward. I use Ctrl+Q to mark other items read as I read them. (Use Ctrl+U to mark messages Unread)
Reading Pane Options Tutorial
[wpvideo KLpSzGnx w=600]
In Outlook 2010 and newer, the Reading Pane options are accessible from the View menu, Reading Pane, Options.

In Outlook 2007 and older, change the settings or disable this option in Tools, Options, Other tab, Reading pane options.
Ziko says
can I use VBA to set the reading pane options?
Ness says
I've begun using the reading pane and respond to messages like this as well. Apart from 'popping' the message out of the reading pane, how can I get options such as follow up and save to a particular folder when sending messages in the reading pane. Is it even possible? It seems there's no information when I search on-line.
F Barnett says
To locate the reading pane right, left, or turn it off in "MY" outlook 2007
I need to select View-Reading Pane. This allows the reading pane to be relocated or turned off completely.
TPetrie says
Hi,
In every message received there is displayed my e-mail address in red - it's very irritating and unnecessary to have that highlighted because I know my email address and I don't need it blaring out to me in red in every line. Any chance you could help me find a way to disable that? I've looked at all the layout options and can't find anything addressing that issue.
Thanks.
Diane Poremsky says
Either you have a conditional formatting rule set up or the sender (or a rule is flagging the message and they are showing as past due.
Margit says
My reading pane has always been "on" and to the right. My computer recently updated and now the default is reading pane "off" and I cannot find a way to change the default when I open outlook. It is driving my boss crazy to change it every time he opens outlook (he also updated recently). Do you know how to change the default so that when we open outlook the reading pane is immediately open and to the right without going to "view" to change it? Thank you!
Diane Poremsky says
Is this outlook 2010? If so, it was an update earlier this month. See https://www.slipstick.com/problems/outlook-starts-safe-mode/ for the registry keys to fix it.
joyfilleddaily says
I wonder if its possible to resize the address header (where it has from, to, cc and subject)?
Diane Poremsky says
No, sorry, it's not. In both reading mode and when composing, you are limited to the sizes microsoft set.
heather says
thanks Diane
heather says
Thanks for your info! Is there a way to make the reading pane appear at the TOP vs. at the Bottom? I know I can do no reading pane, side, or bottom... but I'd like it at the top. Is this possible in any way? Thanks!
Diane Poremsky says
No, sorry, this is not possible.
Gregg says
Thanks for you help- your solution worked!