Yahoo will soon start beta-testing a new version of its free web-based email service. One of the new features this new version will include is a preview pane - much like in Outlook and Outlook Express.
A lot of your recipients never get futher than screening the content of your email in the preview pane, so make sure that you use the top 300-400 pixels of your email wisely! With more and more email clients disabling the downloading of the images in your email -- unless the user specifically requests it -- it is very important that you don't waste this space with images only. The email should also make sense without the images. So be sure to test this before you send!