Where is the "Previous Recipients" info in Entourage? Can it be edited?
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.
You can also clear the entire list in one go by choosing Entourage > Preferences > Mail & News Preferences > Compose, then clicking Clear List.