You can use the Read tab in the Windows Mail Options dialog box to change settings related to how messages are displayed, downloaded, and marked as having been read. To access the Read tab:
Open Windows Mail by clicking the Start button , clicking All Programs, and then clicking Windows Mail.
Click the Tools menu, click Options, and then click the Read tab.
Under Reading Messages, you'll find settings related to how Windows Mail displays messages.
To automatically mark a message as read after you view it for a short time in the Preview pane, select the Mark messages read after displaying for X second(s) check box, and then enter a number in the box. Note that you can change this value to any number from 0, which will mark a message as read as soon as you select it, to 60 seconds. If the check box is cleared, Windows Mail won't mark messages as read when you view them in the Preview pane.
To automatically expand messages when using the Group Messages by Conversation view, select the Automatically expand grouped messages check box. For more information on grouping messages, see Change the way Windows Mail looks.
If you have chosen to display the Preview pane but you only retrieve message headers when checking e‑mail, you might still want to automatically download messages and display them in the Preview pane when you select them in the message list. To do this, select the Automatically download messages when viewing in the preview pane check box.
To disable the display of custom fonts and graphics when reading messages, select the Read all messages in plain text check box.
If you want a tooltip to appear that displays the entire text of an item in the message list when the column is too short to display the full item, select the Show tooltips in the message list for clipped items check box.
To change the color that watched messages are shown in, click a color in the Highlight watched messages list.
Under News, you'll find settings related to how messages are retrieved and managed when you are reading newsgroups.
When you open a newsgroup, Windows Mail automatically downloads the most recent messages. To change how many messages are downloaded, change the number in the Get X headers at a time box to any number from 50 to 1000. To download all headers when you open a newsgroup, clear the Get X headers at a time check box.
If you don't want unread messages to appear as new when you've finished reading a newsgroup, select the Mark all messages as read when exiting a newsgroup check box.
Under Fonts, you'll find options for changing how messages are displayed as you read them.
To choose the font and size used for reading messages, click Font.
To change the default language encoding used for message display, click International Settings.