Rather than using your mouse, use the spacebar to easily go through your mail. Tap the spacebar to go to the next message, or hold down the spacebar to scroll down through a message slowly and continuously.
This shortcut is known by most Mac users, but for if you are new to Mac this shortcut is a time saver.

Comments (3)
I must be doing something wrong. I cannot tracback or forward
using the space bar. Mine does nothing in Entourage 2004 11.3.3
FYI, you can also use shift-spacebar to go back up one page (as in most app, including Safari for instance).
Dick: I'm not sure I understand what you do: here is how it works for me:
in the list of e-mails (regular list, no preview pane), I open the first e-mail then hitting space allows me go go down one page. When I reach the bottom of the page, hitting space again closes the current mesasge and opens the next unread one.
This is only used for reading e-mails. If you want to reply to an e-mail you have to use the regular shortcut (command-r).
In both views: Preview pane on right and below, if you have the message subject selected, you can use the space bar to scroll through the message.