Old email addresses in Mail

When I go to write an email address, I get not only the one I want but every old email address for that person. Sometimes I click the wrong on and send it to a outdated address. How can I remove these addresses and keep them from popping up?

In the mail app, go to the top Menu, then click "Window," then "Previous Recipients. You can remove any or all...

Just an added note -- deleting entries there will have no effect on your address book. All entries there will be intact. Every so often, I go to the previous recipients and delete them all so that I keep things nice and clean and don't take a chance on sending an email to an unintended recipient.

Old names in Mail, coming from Previous Recipients file

In the Window Menu in Mail, about halfway down, select "Previous Recipients".
This opens a window where mail stores email addresses on any address you ever sent an email to.

The small card on the left means the recipient was in your address book when you sent the email.

You can sort the file by clicking any of the headers. If you click on the date column you'll get all your records from oldest to newest. You can delete any one or group that are no longer used.

In addition, if you find an address that you thought you'd lost, you can add it to the address book right from this screen.