You can save time while reading and managing your manager's mail (and your own) by using keyboard shortcuts.
To enable keyboard shortcuts, select Settings from the gear drop-down, and go to the General tab.
Once you’ve enabled keyboard shortcuts, you'll be able to perform common tasks without moving your hands from the keyboard. For example, type “j” and “k” to navigate up and down your Inbox, “o” to open messages, “r” to reply, “a” to reply all, “c” to compose, “s” to add or remove a star, “e” to archive, and much more.
While working in Gmail or Google Calendar, type “Shift+?” at any time to display a complete list of keyboard shortcuts (keyboard shortcuts must first be enabled).
You can find a printable copy of Gmail keyboard shortcuts at http://deployment.googleapps.com/Home/resources-user-adoption/quick-reference/Google_Mail_Shortcuts.pdf
In addition to the “j” and “k” keyboard shortcuts, you can now use the up and down arrow keys to move through your message list. The current message is marked by a blue bar.
To open the current message, just hit Enter.
You can also use your arrow keys to navigate your label list and display a label's messages.
Let's say you’re in your Inbox. Press the left-arrow key to move the focus to your label list. Then use the up/down arrow keys to move through your labels, and hit Enter to display a label's messages.