how to remove incorrect emails from autocomplete?

I've finally had enough so I'm asking for help. I have old or incorrect email addresses that clog up the autocomplete dropdown in mail.app. I've tried everything an IT professional can think of to remove these and they always come back.

Any for sure solutions?

Launch Mail and go to the Window menu. Choose Previous Recipients and a window will appear with the email addresses listed. It also shows the last time each address was used. You can select an entry and either delete it or add it to Address Book.

awesome!