Gmail's Preview Pane enables you to split the screen vertically or horizontally to display selected emails in a separate pane so you can keep your list of emails in one pane while reading them in another. You won't find this feature in the standard settings, however; instead you need to enable this add-on feature through Gmail's Labs. Once enabled, you have to arrange the panes before using the Preview Pane feature.

Step 1

Log in to your Gmail account; then click the gear icon, select "Settings" and choose "Labs."

Step 2

Click "Enable" next to the Preview Pane option and select "Save Changes" to enable the feature and reload your inbox.

Step 3

Click the "Toggle Split Pane Mode" drop-down arrow and select either "Horizontal Split" or "Vertical Split" depending on whether you want the preview pane on the bottom or right side.