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.
Log in to your Gmail account; then click the gear icon, select "Settings" and choose "Labs."
Click "Enable" next to the Preview Pane option and select "Save Changes" to enable the feature and reload your inbox.
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.
- Click any listed email to automatically view it in the preview pane.
- Click the "Toggle Split Pane Mode" button to quickly hide or reveal the preview pane.