How can I automatically save email addresses to my address book?

I have noticed that emails from people I am in correspondence with no longer show up in my address book. This is annoying, when I initiate a new thread, as I have to search for a previous email, copy the email address and paste in into a new mail window. I remember the time, when I could click on an email adress and chose "add to address book", but this no longer seems to exist. That means that transferring data from my email correspondence to the address book is time consuming and boring. Is there a way to automatically add email addresses from outgoing emails to my address book? If so how to I activate this? Hugo