Open the Tools menu and choose Options.
The Options dialog box opens. Click the Other tab.
If you don't want to empty your Deleted Items folder manually, check the Empty the Deleted Items Folder upon Exiting check box.
To make Outlook your default mail program (rather than any other mail programs installed on your computer), check the Make Outlook the Default Program… check box.
You can view and change still more settings using the Other tab in the Options dialog box. This tab enables you to set a hodge-podge of options, including whether items you delete remain in your Deleted Items folder until you manually empty it, which program is your default mail program, and when messages are archived.
Disabling the Person Name SmartTag
When you type a name in an e-mail message's To field, Outlook checks your contact list and displays any matching names. You can press Enter to select the name rather than type it completely. If you do not want to use this feature, you can turn it off by unchecking the Enable the Person Names Smart Tag check box in the Other tab of the Options dialog box.
To view or change the settings for automatic archiving, click the AutoArchive button to open the AutoArchive dialog box.
Select how often the archive is made, whether you are prompted to run the archive, and what happens during the archive.
Click OK to close the AutoArchive dialog box.
Click OK to close the Options dialog box.
Outlook prompts you before running AutoArchive, and does so every 14 days. You can choose whether to run the archive at that time. Outlook archives items older than six montshs, but you can change this interval as well.
Customizing the Preview Pane
To customize how messages in the Preview pane behave, click the Preview Pane button on the Options dialog box's Other tab. In the dialog box that appears, you can, among other things, mark an item displayed in the Preview pane as "read" after so many seconds. Make your changes and click OK to return to the Options dialog box.