We can easily split the Reading Pane to three sections: quick response buttons, message header, and the message content.

Quick Response

At the upper-left corner of the Reading Pane, there are three response buttons: Reply, Reply All, and Forward. You can click the Reply button to reply to the sender of the current selected email immediately, click Reply All button to reply to the sender and all other recipients of the current email, and click Forward button to forward the current email.

Message Header

In the message header section, you can get multiple information about the current selected email: the sender, recipients, subject, received date, attachments, total number of attachments, etc.
 
Sometimes, the message header section does not display fully. You can click  at the bottom-right corner of this section to expand it. On the contrary, click  to collapse the message header section.

The attachments are listing in the Attachment Bar. You can directly save, select, print, copy and remove attachments with the right-clicking menu of attachments.

Message Content

By default, this section will preview the message content of the current selected email, and preview its attachments as well.

If you click on an attachment in the Attachment Bar, it will preview the attachment content in this section instead.

When previewing an attachment, you can click Back to Message at the upper-left corner of the Reading Pane to preview the message content again.

You can change the preview zoom level of the Reading Pane by the Zoom Slider at the bottom-right corner of the Outlook interface.

Turn off the Reading Pane

By default, the Reading Pane if turned on in Outlook. You can click View > Reading Pane > Off to turn off it.

Turn on the Reading Pane

If the Reading Pane has been turned off, you can click View > Reading Pane > On to turn it on.

Move the Reading Pane

By default, the Reading Pane is placed on the right side of the Message List. You can click View > Reading Pane > Bottom to move it to the bottom of the Message List, and click View > Reading Pane > Right to restore it to the right.

You can configure the Reading Pane options for previewing emails in the Reading Pane.

1. Click View > Reading Pane > Options.

2. In the Reading Pane dialog, you can configure below settings:

(1) Mark items as read when view in the Reading Pane: If enabling this option, the unread emails will be changed to Read automatically after you open the email in the Reading Pane for the given number of seconds.

(2) Mark item as read when selection changes: If enabling this option, the current opening email will be changed from unread to read automatically after you open another email in the Reading Pane.

(3) Single key reading using space bar: If enabling this option, you can use the Space Bar to scroll through pages of the current selected message in the Reading Pane, and move to the next email when reaching the end of the current email. And use Shift + Space Bar to move to the previous message.

(4) Turn on automatic full-screen reading in portrait orientation: This is an option for the tablet users. And when the tablet is in portrait orientation, clicking an email will display it in full screen.

(5) Always preview message: When this option is turned off, it will display “Select an item to read” in the Reading Pane when you navigate to a folder for the first time after launching Outlook. If checked this option, it will always display the most recent message in the Reading Pane when navigate between folders.