Apple's Mail application, similar to many modern e-mail clients, contains a function that remembers previous recipients. As more people change e-mail addresses for work, because of a hacked account, being spammed, or just to try out a new e-mail service, it gets harder to maintain your contact list. While many users change or delete e-mail addresses in Address Book, they are finding the old addresses keep appearing in the auto-filled To: field in new messages.
