If they were not in one of your address books they would not be suggested. You have at least two default address books. Find the entries and delete them.

If you have trouble finding the bad contacts in the address books it could be because they were saved without a name or other important info stored in the address book. Start a new message and when the bad contact address is suggested, select it and create a message. Save it to Drafts. Go to the drafts folder and click on the message so it displays in the Message Pane. Press F8 to turn on the Message Pane if not already on. Look at the Message Pane header and double click the contact name there to open the Edit dialog box. Delete the bad contact from there.