Gmail had a cool Labs feature that allowed you to read messages without opening them. Message Sneak Peek displayed the first sentences from a message when you right-clicked it. You could use keyboard shortcuts to navigate to the previous or to the next message, so this was a great to quickly read messages.
Here’s a screenshot from 2010, when this feature was launched:
The Labs experiment is no longer available and now Gmail has a contextual menu that shows features like “move to inbox”, “archive”, “delete”, “mark as read/unread”, “move to tab” (for inbox messages). You can select multiple messages, right click and use one of the features that were also included in the Gmail toolbar.
If you’re missing Sneak Peek, try Preview Pane, another Labs experiment that lets you read messages in a vertical/horizontal pane like in Outlook or Gmail for tablets.
{ Thanks, jp (banana). }