Where is the previous recipients info in Entourage?
You can do it, though it's done in kind of an odd fashion.

From the Entourage 2008 Help file:

To delete a single entry from the recently used address list, you must first add it to your address book and then delete it from your address book.


Click Mail, and then click New.
In the To box, type the first few letters of the address. A list of suggested addresses appears.
On the pop-up menu of addresses, click the recently used address that you want to delete.
Press CONTROL, click the address, and then click Add to Address Book. The address appears in a new contact.
On the Edit menu, click Delete Contact. If a confirmation message appears, click Delete.
Close the message, and then click Discard Changes.


You can also clear the entire list in one go by choosing Entourage > Preferences > Mail &amp; News Preferences > Compose, then clicking Clear List.